Social Forestry in India

Indiscriminate abuse of the forests concerning since the mid 20th century led to deforestation and it was the rural poor of the country who was affected most by burden on forests. Degradation of forest resources aggravated the problem of poverty, unemployment and scarcity of food, fodder, fuel, timber etc. among this section of the society. There was felt a need, therefore, to undertake tree plantation programs involving these rural poor, primarily to meet their own needs from the trees.

What is social forestry?

The traditional forestry is mainly involved in the protection of trees and their production, where as social forestry is concerned to welfare of the society, particularly the rural poor who depend for most of their livelihood requirements on forests. Social forestry does not only helps in rehabilitation of degraded land but also provides opportunities of employment to rural poor.

Social forestry

Birth of social forestry

Forest wood provides roughly 43% of the energy consumption by the developing world. In India, biomass constitutes about 85% of the rural energy and roughly 50% of it comes from the forests. Besides a source of wood, forests also help in agricultural production, clean environment and biodiversity conservation. Since ancient times forests have been a substantial support to rural economy of India. Over 60% of the Indian population is directly dependent on forest for fuel, fodder, fibre, timber, medicine, food etc. Moreover, forests also provide job to roughly 20 million people around the year throughout collection of non wood forest products, and for over 50 to 60 million people, forests are a part of their culture and a natural way of life.
In India, out of the total land area of 329 million hectares, 143 million hectare is under agriculture, and 77 million hectares classified as forest. the forest area of the country is hardly 2% of the world's forests, where as it is home of 15% of the world population. The traditional communities had been living comfortably in perfect harmony with the forests using them judicially to meet their needs following proper management practices. However, with increasing growth of human and livestock populations and a shift in the ownership of natural forest from the the princely states to the Federal government, the control and moral pressure on the local population was relaxed, leading to discriminate abuse of forest since the middle of 20th century. Unable to meet their basic needs from agriculture, many unemployed and poor families turn to for is not only for fodder and fuel, but also to generate cash income through sale of wood and other forest products. Vested interest also took this opportunity to exploit forest for commercial purpose.

Apart from biotic pressure, the following factors also contributed to the denudation of forest resources (GOI, 1984).
* Increase in human and livestock     populations;
* Inadequate scientific and technical inputs;
* Inadequate skills and training of the staff to play their expected new roles;
* Poor investment on forest development; 
* Poor management of forests
* Damage caused by mining, irrigation projects, industries, roads and jhum cultivation.

The abuse of forests continued unchecked till mid 1970s, when the ill effects of deforestation were prominent in the form of fodder and wood fuel scarcity, soil erosion, flash floods, water scarcity, loss of precious flora and fauna and climate change. By 1981, the area under wastelands in India was estimated at 93.70 million hectares, excluding the degraded agricultural lands measuring over 85 million hectares. Most of the natural forests around the villagers had turned into wasteland reducing the area under forest to only 40 million hectares. Over 30 million hectares of community pastures were devoid of vegetation due to overgrazing by 450 million heads of livestock. Due to non availability of wood on village common land, rural women were compelled to spend 15-35 hours was every week in walking learn distances for collecting fuel wood from interior forests. As a result of deforestation,the damage from floods affected 58 million hectare of agricultural land and over 60 million people during the 1980s. The extent of damage had increased by folds over the earlier two decades.

The rural poor, particularly the women, who are primarily responsible for fetching water, fodder and fuel were faced with severe drudgery. The community felt that while it was the responsibility of the forest department to manage the forest, it was their inherent right to collect fodder, fuel and other products from the forest, without any obligation. Planting of trees for fodder and fuel was never considered by the farmers as a necessity. Meanwhile, faced with a shortage of biomass, many village communities resisted the extraction of wood from the forest for commercial purposes. This led to the involvement of rural communities in forestry development programs in India.

In 1976, the National Commission on Agriculture in India introduced the concept of social forestry to encourage those who were dependent on fuel wood, fodder and other products, to meet their own needs through various activities, in order to reduce the burden on forests. This concept was further defined by FAO in 1978, by defining community forestry as the program which intimately involved local people in a afforestation, irrespective of the pattern of land ownership. While the traditional forestry cover the protection and production roles, social forestry was intended to play the social role.

Bio-Medical Waste : Source of Deadly Diseases

The state of Gujarat and entire nation all of sudden were put on alarm due to sudden outbreak of hepatitis. The total number of people with hepatitis infection has reached 184, out of which 56 have already died. The uprovar over the spread of this deadly virus triggered off a drive to check unsafe medical practices. It led to discovery of an appalling racket - bio-medical waste recycling. More than 50 tons of biomedical waste have been recovered from several scrap dealers across the state. They buy used syringes, needles, multiple vials, IV sets, empty medicine bottles, catheters and even blood bottles, which have crossed the stipulated expiry dates and recycle them back to the doctors!

What is biomedical waste?

Biomedical waste is any waste, which is generated during the diagnosis, treatment for immunization of human beings or animals. It also includes the waste generated during research activities involving the production or testing of biologicals, which means any preparation made from organisms are microorganisms are product of metabolism and biochemical reaction.

Sources of biomedical waste

Common producers of biomedical waste include hospitals, nursing homes, other health Care units, pathological and research laboratories, blood banks, veterinary institutions, home healthcare, funeral homes and animal slaughter houses.

Disposal of biomedical waste

There are various methods of dealing with biomedical wastes, including incineration, deep burial, autoclaving, microwaving, chemical disinfections, shredding and disposal in municipal landfill. 

Biomedical waste Management

The management of biomedical waste is crucial issue in health and environmental management. It is estimated that India generates more than 3 lakh tonnes of waste, annually. The solid waste from the hospitals consists of bandages, linen and other infectious waste, cottons swabs, disposable syringes, glass and other general wastes including food.

Out of these, the biomedical waste has to be disposed on accounting to the biomedical waste ( management and handling) rules 1998. It directs the followings:

• To set up the requisite biomedical waste treatment facilities like incinerators, autoclave, microwave system for the treatment of waste or ensure requisite treatment of waste at a common waste treatment facility or any other waste treatment facility.

• Biomedical waste shall not be mixed with other wastes.

• Biomedical waste shall be segregated into containers or bags at a point of generation.... Prior to its storage, transportation, treatment and disposal. The container shall be labelled.

• No untreated Biomedical waste shall be kept or store beyond a period of 48 hours.

• Every authorised person shall maintain records related to the generation, collection, reception, storage, transportation, treatment, disposal and/or any form of handling of bio medical waste in accordance with these rules and any guidelines issued.

• All records shall be subjected to inspection and verification by the prescribed authority at any time.

 

The proper management of Biomedical waste has several aspects : political, social, economic, technical and of course, environmental. We must have adequate knowledge of the types of waste, how much is being produced, who produces it, and what happens to it. This will help us to know what should be done with waste,  and prepare for the future.

There are following certain aspects that must be taken into account:

• Before increasing institutions for managing the biomedical wastes, it is necessary to carry out an environmental impact assessment (EIA). This will spread awareness among people about the environmental effects of dumping of Biomedical wastes.

• Community based waste management for treatment facility must be emphasised.

• The management practice must monitor land use planning, and prohibit or impose restrictions on undesirable land used for dumping the biomedical wastes. There are two blocks : there is "limited land resource;  and there is not set "perfect rule", which can be followed.

• The handling of such wastes requires constant monitoring by a specific agency. There should also be periodic monitoring of the level of pollution. So, it is necessary to have a strong enforcement mechanism within the framework of law. it becomes the duty of the owner of the institutions to active responsibility in dealing with such hazardous substance.

Noise Pollution

The human ear is constantly being assailed by man made sounds from all sides, and there remain few places in populous areas where relative quite prevails. What do aeroplanes, trains, car and pneumatic drills, and radio and television sets have in common? They all produce noise, the most dangerous pollutant of humans environment. nice has become a permanent part of our lives these days because of the development of machinery, industry and technology. Noise harms the body and mind. Noise not only cause irritation or annoyance but it constricts your arteries, increases the flow of adrenaline and forces your heart to work faster.

The word noise is usually defined as unwanted or unpleasant sound that causes discomfort. Noise is also defined as "wrong sound, in the wrong place at the wrong time". Noise pollution means "the unwanted sound dumped into the atmosphere leading to health hazards".

Formerly noise was limited only to the industry. This too was not much as there were only few industries. These bhej there has been rapid industrial growth. More ever, there has been population explosion, due to which there is heavy traffic, urban crowd and electric equipment. All these have added to the night nuisance in environment. In our country, besides these the two other factors are religious and social functions which increase the gravity of situation. 

Sources of noise

The main contributors to noise are factories and industries transportation and community and religious activities. there should not be an exaggeration to say that we Indians are energy per and every sentiment and location is manifested in a noisy manner - be it a religious occasion, elections or a family celebration.

The chief man made sources in urban areas are automobiles, factories, industries, trains, aeroplanes. Noise makers are horns,  sirens, lawn movers,  musical instruments, TV, radio, transistors, telephone, dogs, loudspeakers, washing machines, vacuum cleaner, food mixers, pressure cookers, fans, air conditioners, air coolers. Ever since the industrial revolution, there has been doubling every 10 years of environmental noise.

Properties

There are two basic properties of sound, (1) loudness and (2) frequency.

Loudness is strength of sensation of sound perceived by the individual. It is measured in terms of decibels. Just audible sound is about 10 dB, a whisper about 20 dB, library place 30 dB, normal conservation 35 to 60 dB, heavy Street traffic 60 to 80 dB, boiler factories 120 dB, jet planes (take off) about 150 dB, rocket engine about 180 dB. The loudest sound a person can stand without much discomfort is about 80 dB. Sounds beyond 80 dB can be safely regarded as pollutant as it harms hearing system. The WHO has fixed 45 dB as the safe noise level for a city. For international standards a noise level up to 65 dB is considered tolerate. Mumbai, New Delhi, Kolkata and Chennai usually register more than 90 dB. Loudness is also expressed in sones. One sone equals the loudness of 40 dB sound pressure at 1000 hz.

Frequency is defined as the number of vibrations per second. It is denoted by Hertz (hz). 1 hz equals to 1 vibration per second. People can hear sound from 16 (infra audible) to 20000 (ultrasonic) hz.

Effects of noise pollution

The different effects are categorised as (1) auditory effects (affecting hearing faculty) and (2) non auditory effects (other than auditory ones).

Auditory effects

These include auditory fatigue, and deafness. Auditory fatigue appears in the 90 dB and may be associated with the side effects as whisling and buzzing in ears. Deafness can be caused due to continuous noise exposure. Temporary deafness occurs at 4000 to 6000 hz. Permanent loss of hearing occurs at 100 dB. Mumbai and Kolkata are the noisiest cities in the world. Many persons have risk of deafness.

Non auditory effects

These are interference with speech communication, annoyance, laws of working efficiency and physiological disorders. 

Interference with speech communication

A noise of 50 to 60 dB commonly interferes with speech; sound of warning signals may be misunderstood.

Annoyance

Balance person express great annoyance at even low level of noise as crowd, highway, radio etc.

Loss in working efficiency

There develop tiredness and those doing mental work may put to deterioration in their efficiency or even complete loss of ability to work.

Physiological disorders

There develop a number of physiological disorders due to imbalance in functioning of the body. These are neurosis, anxiety, insomnia, hypertension, hepatic diseases, behavioural and emotional stress, increase in sweating, giddiness, nausea, fatigue etc. Noise also cause visual disturbance, and reduce depth and quality of sleep does affecting overall mental and physical health. Other effects are undesirable changes in respiration, circulation of blood in skin and gastrointestinal activity.  Noise pollution also causes incidence of peptic ulcers.

                                                                              Continuous noise causes an increase in cholesterol level resulting in the constriction of blood vessels making you prone to heart attack and strokes. There may be still births and usually low weight children born to mothers living near airports.

Supersonic airplanes create a shock wave called Sonic boon, which produces a startle effect that can be  more harmful than a continuous noise. The Sonic boon may spread in an area of 10 to 80 miles and when it hits the ground it damages window pans and building structures. This may also faster in the human foetus heartbeat rate. 

Acid Rains : An Invisible Threat

Oxides of sulphur and nitrogen are important gaseous pollutants of air. These oxides are produced mainly by combustion of fossil fuels, smelters, power plants, automobile exhaust, domestic fires etc. These oxides are swept up into the atmosphere and can travel a distance of thousands of kilometres. The longer they stay in the atmosphere, the more likely they are to be oxidized into acids. Sulphuric acid and nitric acid are the two main acids, which then dissolve in the water in the atmosphere and fall to the ground as acid rain or may remain in atmosphere in clouds and fogs.
Acidification of environment is man made phenomenon. The acid rain is in fact a Cocktail of sulfuric acid and nitric acid and the ratio of the two may vary depending on the relative quantities of oxides of sulphur and nitrogen emitted. On an average 60 to 70% of the acidity is ascribed to sulfuric acid and 30 to 40% to nitric acid. The acid rain problem has dramatically increased due to industrialisation. Burning of fossil fuels for power generation contributes to almost 60 to 70% of total sulphur dioxide emitted globally. Emission of nitrogen dioxide from anthropogenic sources ranges between 20 to 90 million tonnes annually over the globe. Acid rains have a global ecological problem because oxides travel a long distance and during their journey in atmosphere they may undergo physical and chemical transformations to produce more hazardous products.

Acid rains create complex problems and their impacts are far reaching. They increase soil acidity, thus affecting land flora and fauna;  causes acidification of lakes and streams does affecting aquatic life, affects crop productivity and human health. Besides these they are also corrodes buildings, monuments, statues, bridges, fences, railings etc. British Parliament building also suffered damage due to sulfuric acid rains. Due to acidity, levels of heavy metals like aluminium, manganese, cadmium, lead and copper in water increases beyond the safe limits. Over 10,000 lakes in Sweden have become acidified. Thousands of lakes in USA, Canada, Norway have become unproductive due to acidity. Fish population has decreased tremendously, and there are deaths of Salman trout etc. The fishless areas are now fish graveyards.
Many bacteria and blue green algae are killed due to acidification, the judge disrupting the ecological balance. In West Germany nearly 8% of the forests died and nearly 18 million acres of forest are critically affected by acid rains. Forests in Switzerland, Netherlands and Czechoslovakia have also been damaged by acid rains. Nutrients as calcium, magnesium, potassium have been leached away from the soil by acids.

Acid rains are great threat to  British environment as to  Central Europe and southern Scandinavia. in 1974 acid rains over Scotland were found to be more sour than vinegar.
Acid rains are carried away by 
prevailing winds to elsewhere where precipitation takes place. The oxides may be produced at one place, and these effect elsewhere by turning into acids. The two such victims are Canada and Sweden. Canada gets acid rains from petrochemical units in North America. Heavy winds pickup acid rain from factories in Britain and France to Sweden. Equally grim are the acid rain in Norway, Denmark and West Germany. It is said that 90% of the acid rain of Norway and 75% of Sweden are due to drifted acid rain oxides.

Though acidity of rainwater is yet to be adequately monitored, developing country like ours may soon have to face the acid rain problem. The acid rain is fast spreading to developing world where tropical soils are even more vulnerable than those of Europe. It appears that acid rain problem is on The avil in India. Industrial areas with the pH value of rainwater below or close to the critical value have been recorded in Delhi, Nagpur, Pune, Mumbai and Kolkata. this is due to sulphur dioxide from coal based power plants and petroleum refinery. According to a study made by BARC monitoring section; the average PH value of acid rain in Kolkata is 5.80, Hyderabad 5.73, Chennai 5.85, Delhi 6.21 and Mumbai 4.80. The situation may even worse and in future due to increased installation of thermal power plants by NTPC and consequent increase in coal consumption. According to one estimate total emission of sulphur dioxide in India from fossil fuel burning has increased from 1.38 million tonnes in 1966 to 3.20 million tonnes in 1979, a 21% increase as compared to corresponding increase of only 8.4 % in USA during the same period. There is urgent need for proper regular monitoring to provide timely warnings about acidification of our environment.

The great Indian desert (Thar Desert)

This is an area in which the vegetation cover is par and the ground surface is the exposed to the atmosphere and the associated physical forces. Rainfall is scanty, infrequent and irregular. the desert is the Eastern section of the Sahara Arabian desert and is also known as Thar desert (earlier it was known as Tharparkar desert; Tod Rajasthan). Thar desert extends over 1.3 million square kilometre; it is half of the Arabian desert and one seventh of the Sahara desert. 

Climate

The climate is characterized by extremes of temperature, severe draught accompanied by high wind velocity, low relative humidity, evaporation for more than rainfall and to scanty rainfall to support any appreciable vegetation.

The winters are quite cold, temperatures, sometimes below freezing point while heat during summer is intense and scorching. Hot season prevails from April to June, May being the hottest. The mean maximum temperature ranges from 39 degree Celsius to 42 degree Celsius during these months, whereas the mean minimum temperature ranges from 25 degree Celsius to 28 degree Celsius. December to January is cold weather, January being the coldest.

Rainfall is scanty and erratic with 10 cm  or more rains. Average rainfall for the last 10 years is 315.26 mm, 302.14 mm (Barmer). Most rainfall occurs during monsoon period of June to September. Winter rains are rare. Droughts occur quite frequently.

The wind from South-west to West is most common. Dust storms - Andhis  are quite frequent and in hot weather may be as strong as 136 kilometre per hour. In winter comma velocity is not hai. Rainfall is often associated with easterly winds.

                          Soil

Light texture and the loams form the bulk of soil. The layer of loose sediment is fairly deep. Clay is less in surface layers but may be up to 40% in the lowest layers. Salt impregnated patches occur throughout the area, particularlyc in Pachhadra in Barmer, Phalodi in Jodhpur and near Ramgarh in Jaisalmer district where halophytes abound. However consists of Sandy plains.

              Physical features

Pleistocene alluvial plains varying cover by younger wind worked sands constitutes by far the most extensive feature of the arid region. These plains have an elevation of 350 to 450 metre above the mean sea level.

Most spectacular among the landforms are the the dunes, which in arid Rajasthan cover, in varying degrees of frequency, 58% of the area. Dunes occur in two major chains- one lying in the western part of Barmer, Jaisalmer and Bikaner districts, made up of often 20-100 m high and many kilometres long dunes, and the other covering Eastern part of Bikaner and churu districts.discontinuous dune fields are scattered in the major part of the raised area. The dunes are of six types - obstacle, parabolic and coalesced parabolic, longitudinal, transverse, barchan and shrub coppice.

Phosphorus cycle

The great reservoir of phosphorus is not the atmosphere but the rocks or other deposits which have been formed in past geological ages. These are gradually eroding, releasing phosphates to ecosystems, but much phosphate escapes to the sea, where part of it is deposited in the shallow sediments and part of it lost to the deep sediments. The means of returning phosphorus to the cycle may presently be inadequate to compensate for the loss. Marine birds and fish may play important role in uplifting of sediments thus returning phosphorus to the cycle. This transfer of phosphorus and other materials by birds from the Sea to land is continuing but not at the rate it had occurred in some of the past ages. Man harvest lot of marine fish , , thus accelerating the rate of loss of phosphorus but not enough being cycled as compared to the phosphorus  in parent rocks.

Though, reserves of phosphate Rock are large, situation could become alarming, and we feel concerned with "traffic jam" of dissolved phosphate in the waterways due to increased erosion that may not be compensated for by protoplasm synthesis and sedimentation. One way to overcome this problem is to spray waste water on upland vegetation instead of piping it directly into the water ways.

It may be concluded from above that generally, phosphorus does not move evenly and smoothly from organism to environment and back to organism as it appears from the figure.

There may be achieved a long term equilibrium. Most phosphorus at a time, is tied up either in the organisms (bone) or in solids (organic detritus and inorganic particles making the sediments). In lakes, generally uptake rate is more rapid than the release rate. Concentration of phosphorus at any one time may bear little relation two productivity of the ecosystem. March aur virtually all of the phosphate in the system may be inside living organism at a given time, yet it may be overturning every however with the result that there will be a constant supply of phosphate for organisms able to concentrate it from a very dilute solution. Such systems may remain stable biologically for considerable periods in the the absence of available phosphate.

The concept of turnover is very useful in comparing exchange rates between different components of an ecosystem. Turn over rate is the fraction of the total amount of a substance in in a component which is released any given length of time, whereas turn over time is the reciprocal of this that means the time required to replace quantity of substance equal to the amount in the component. studies with P - 32 labelled fertilizers in land ecosystems have also revealed that much of the phosphorus is locked up and unavailable to plants at any given time.

Impact of human activities on phosphorus cycle

✓ We mine large quantities of        phosphate rocks to make commercial inorganic fertilizers and detergents.

✓ We reduce the available phosphate in soils by cutting down forests.

✓ We disrupt aquatic systems with phosphates from runoff of animal waste and fertilizers and discharge from sewage treatment systems.

Biodiversity of India

India is one of the 12th Mega biodiversity countries of the world. Each of the ten biogeographic zones of the country has characteristic biodata and broadly represent similar climatic conditions and constitutes the habitat for diverse species of flora and fauna. Based on a survey of about two third of the geographical area of the country, the ministry of forest and environment reported that India have at present about 45000 plants and 77000 of animals species representing about 7% of the total flora and 6.5 % of the world faunna respectively, representing about 6.5 % of the Global biodiversity.

A significant feature of the Indian Flora is the Confluence of floras from the surrounding countries like Malaysia, China, Tibet, Japan and Europe and even from distant country like America, Africa and Australia. India is also very rich in its crop biodiversity, it has repositories of over 50,000 varieties of rice and 5000 varieties of sorghum and 1000 varieties of mango.

Value of Indian biodiversity

India occupies a unique position among global biodiversity as a mega biodiversity Nation. A large number of species are native to India.it is stated among the top ten or fifteen nations of the world for its great diversity of plant life, especially flowering plants, a source of new drugs being discovered during the recent past. About 5000 species of flowering plants belonging to 141 genera and 47 families had birth in India. We are equally rich in insects, amphibia, reptiles, bird and mammalian species of great economic potential. Many of these are endemic to India, found nowhere else in the world. India is a source of traditional crop varieties ranking first among the 12 regions of diversity of crop plants and 7th so far in the contribution of agricultural species. India is the origin place of about 175 species of crop plants and about 350 species of wild relatives of cultivated crops.

           Out of the total number of flowering plant species known in India, there are more than 4000 species used in medicines, about 3,000 for food, nearly 700 as a traditional religious and social purpose, about 500 yield fibre, 400 as fodder, 300 yield gum and about hundred species are used to extract essential oils and scents. India has been primary centre for domestication of rice, sugarcane, banana, mango, cucumber, citrus, cucurbits, beans, jute, black pepper, Ginger, turmeric, yam, taro, bamboo and jackfruit and secondary centre for domestication of potato, tomato, maize, seasame and soybean.

India is rich in Marine biodiversity among the coastal line of 7500 kilometre with exclusive economic zone of 202 million square kilometres, supporting the most productive ecosystem such as mangroves, coral reefs, estuaries, lagoons and backwaters. there are about 45 species of mangrove plants over 342 species of coral reefs belonging to 76 genera have been reported and about 50% of global reef building corals are found in India.

Endemic species of both plants and animals are mostly found in North-East, Western ghats and Andaman and nicobar islands.in Western ghats and north east Himalayas about 1500 and 2000 species of plants and animals respectively are endemic. About 33% of Indian endemic species belongs to flowering plants.

Among animals, 135 genera have been reported as endemic, of which 85 (63%) are found in North East India. Birds, representing about 14% of global avian fauna show relatively high endemism. Among reptiles, 50% lizards are endemic, whereas 62% of amphibians are endemic, mostly in Western ghats. Marine sediment worms, sponges and mayflies show high endemism.

Indian society has realised the value of its biodiversity since ancient times, conservation it as sacred groves, sacred seeds and sacred species. Biodiversity rich ecosystems are natural resources of our agriculture, livestock, forestry and fisheries. Indian biodiversity is a source of several life saving drugs and normal chemicals. About 90% of all Indian medicines are obtained from plants. Many of the medicinal plants are being robbed by the pharmaceutical companies from the third world countries, including India.The major pharmaceutical companies of some developed countries such as American national Cancer institute, bristol-Meyers, Glaxo, Merck, Sharp Dohne Research Lab, Monasasto/Searle, Shaman pharmaceuticals and Smithkline Beecham are now actively involved in procuring information about traditional knowledge of such natural medicines. The flora and fauna including bacteria, algae, fungi, gymnosperms, flowering plants, protozoa, corals, sponge, animals are being screened by such companies/ institutions for natural products to develop drugs.

                           It is interesting to note that many plant diversity rich countries have a low per capita income, and the financially rich countries have poor plant diversity.

The atmosphere

The vast expanse of air which envelops the earth is called atmosphere. Among the four elements of environment, the atmosphere is the most dynamic as changes takes place in it not only from one season to another but also over shorter periods of a few hours.The atmosphere extends to thousands of kilometres above the Earth's surface but it has no well defined upper limits and gradually merges with the outer space. Of the total mass of the atmosphere, about 99% is within a height of 30 kilometre from the Earth surface.It is within this layer that most of the atmospheric changes take place.

           The atmosphere contains life giving gases like oxygen for man and animals, and carbon dioxide for plants to be used in manufacture of food. It acts like a greenhouse by trapping the heat.like the glass in a greenhouse, the atmosphere allows shortwave radiation to enter it and reach the earth surface.atmosphere protects the earth from the harmful radiation from the sun. It also serves as a storehouse for water vapour which leaves the precipitation fairly distributed over land and sea. The presence of air and water on the earth makes it a unique planet in the solar system.

Structure of atmosphere

The atmosphere consists of almost 

concentric layers of air with varying density and temperature. Density is 

highest on the earth's surface and decreases rapidly upwards. In the atmosphere,  broadly 5 layers can be identified i.e troposphere,  stratosphere, mesosphere, ionosphere and the exosphere.

Troposphere

This is the lowest layer of atmosphere, thus laying closest to the Earth's surface. it extends roughly to a height of 8 kilometre near the poles and about 18 kilometre at the equator. It is thickest at the equator as heat is transported to great heights by strong conventional currents.temperature in this layer decreases with increasing height, roughly at rate of 1 degree Celsius for 165 metres of ascent.this is known as normal lapse rate. Troposphere contains dust particles and over 90% of the earth's water vapour. All important atmospheric processes leading to various climatic and weather condition take place in the troposphere, hence most significant layer.aviators of jet aeroplanes are often avoid this layer due to presence of bumpy air pockets.

Stratosphere

It lies beyond the troposphere, and the zone separating the two is called tropopause. Stratosphere extends upto a height of 50 km. Temperature ceases to fall, and remain constant up to a height of 20 kilometre.afterwards it gradually increases up to a height of 50 kilometre due to presence of ozone layer which absorbs the ultraviolet radiations of sun. Clouds are almost absent and very little dust or water vapour. The air movements are almost horizontal. air temperature at the tropopause is about - 80 degree Celsius over the equator and about -45 degree Celsius over the poles. 

Mesosphere

this is the third layer over the stratosphere extending up to a height of 80 kilometre. Temperature decreases with height again reaching up to -100 degree Celsius at the height of 80 kilometre.

Ionosphere

The fourth layer, ionosphere is located between 80 and 400 kilometre. it is an electrically charged layer, in which ions reflect radio waves back to the Earth surface and enable wireless communication. Temperature again starts increasing with height due to radiation from the 🌞.

Exosphere

This is the uppermost layer of atmosphere extending beyond the ionosphere above a height of about 400 km. This layer is extremely rarefied and gradually merges with the outer space.

 

Leaves of Dicot plants Showing reticulate venation

 

     

       Guava leaves                                                        Mulberry leaves
    (Psidium guajava)                                                     ((Morus alba)

                           

                                 Neem                                                       Crape Jasnine                                             
                      (Azadirachta indica)

                                                                Plumeria (Chafa)

These are the leaves of dicot plants. The leaves of these plants have reticulate venation.

Agroforestry in India

Though Agroforestry has been defined in different ways, the substance of each definition is the same. Put simply, agroforestry is using trees on farms. Trees can provide many products such as fuel, wood, fodder, Timber, medicine and oil.

                                                            Agroforestry is a collective name for land use systems involving trees combined with crops and or animals in the same unit of land. The land thus can be used to raise agricultural crops and trees and to rear livestock. Agroforestry is Defined by some as a dynamic, ecologically based natural land/farm management system that, along with agriculture and the integration of trees on forms, has many environmental merits.

                                                     Agroforestry combines agriculture and Forestry Technologies to create more integrated, diverse, productive, profitable, healthy and sustainable land-use systems. 

Agroforestry is, therefore , a system of farming that combines the planting of trees and food crops in a way that is beneficial for the farmer and the environment.

The practice of Agroforestry is in no way a new system of land use. Ever since man began  cultivating crops and domesticating animals, he has been practicing Agroforestry. In fact, farmers in India grow agricultural crops, rear animals, and plant some trees on their land, often on boundary area. However, the increasing need of this system was in fact realised during the mid 20th century with loss of forest cover of India at alarming rate and increase in wasteland areas due to urbanization and industrialization. The Agroforestry program in India were started in the late 1970 as a result of the recommendations of the National Commission on agriculture. This led to the various social Forestry projects which provided the farmers additional income from the sale of timber and other means of substances like fuelwood, fodder and non -wood forest products. Some examples of Agroforestry are, growing of tea and coffee under the shades of tree, intercropping under coconut trees, home Gardens and shifting cultivation.

Agroforestry reduces the farmers dependency on forest even as it provides them economic benefits. IT results in more diverse, healthy, and sustainable land use systems. It focuses on meeting the economic, environmental, and domestic needs of people on their private lands. For hundreds of years, farmers have nurtured trees in their fields, pasturelands, and around their homes. Agroforestry does help in increasing productivity of Crop plants and meeting increasing demands of order and fuelwood through afforestation.

                         Different farming systems are in use in different parts of the country. These include agrisilviculture ( eucalyptus and poplar with crops) in Northern States, the early Taungya system (sal forest raising with crops),farm boundary tree plantations, homestead gardening and multitier backyard system in Kerala, energy plantations in Gujarat, Maharashtra, Karnataka, Andhra pradesh, Tamilnadu etc; silvipastrol  systems with community Forestry programs and roadside plantations with social Forestry departments of various state and shifting cultivation of north eastern hill States.

Taungya system

It is a system of establishing three crop in temporary combination of field crops. This system was first attempted in Myanmar by Brandis in 1856 and subsequently in India during 1911 - 12 for raising Shorea robusta and Tectona grandis plantations. This technique was even used for secondary forest species or even for Acacia nilotica - firewood species. This system failed with deodar forests but was successful with Cryptomeria, oaks and Michelia species. 

Greenhouse Effect

Under normal conditions the temperature at the surface of the Earth is maintained by the energy balance of the sun rays that strike the planet and heat that is radiated back into the space. The layer of this gas prevents the heat from being re-radiated out. This carbon dioxide layer thus functions like the glass panels of a Greenhouse, allowing the sunlight to filter through but preventing the heat from being re-rediated in outer space. This is so called natural greenhouse effect.
       But when there is an increase in carbon dioxide concentration as pollutant most heat is absorbed by CO2 layer and water vapour in the atmosphere, which adds to the heat that is already present. The net result is the heating up of the earth's atmosphere. This is called enhanced greenhouse effect. Thus increasing carbon dioxide levels tend to warm the air in the lower layers of atmosphere on a global scale. Nearly 100 years ago the carbon dioxide level was to 75 ppm. Today it is 350 ppm and by the year 2035 and 2040 it is expected to reach 450 ppm. Now imagine the earth's temperature. Carbon dioxide increases the earth temperature by 50% while chlorofluorocarbons are responsible for another 20% increase. There are enough chlorofluorocarbons up there to last 120 years. What will happen if we do not stop CFC release?
                                                                                        The heat trap provided by atmospheric carbon dioxide probably help to create the conditions necessary for the evolution of life and the greening of Earth. Compare to moderately warm planets, Mars with too little carbon dioxide in its atmosphere is frozen cold and Venus with too much is a dry furnace.
                The excess of carbon dioxide to some extent is absorbed by the oceans. But with the industrialisation of waste and increased consumption of energy, carbon dioxide was released into the atmosphere at a faster rate than the capacity of oceans to absorb it. Show the concentration of carbon dioxide in atmosphere increased.
                                                             According to some, computerized models, doubling the carbon dioxide level will increase the Global mean temperature by 2 degree Celsius. But some others say that this will be less than one-quarter of a degree. There are other gases also which contribute to greenhouse effect. These are Sulphur Dioxide, Nitrogen dioxide and CFC's discharged by the industry and Agriculture. Even a change of two degrees may disrupt the earth heat budget, causing Castrophic consequences.
                                                                            Some people believe that changes in the earth's mean temperature will be Apparent by 2050 when the temperature would increase by 1.5 to 4.5 degree Celsius. According to one projection, changes will be the least in the tropics and the most at the poles. So, Greenland, Iceland, Norway, Sweden, Finland, Siberia and Alaska will be among the most affected. The polar ice caps would melt. The floating Western Antarctica Ice sheet could begin to melt.  Rise of 5°C would raise the sea level by 5 metres within a few decades, threatening all the densely populated coastal cities from Shanghai to San Francisco. It is suggested that North America would be warmer and drier. The United States would produce less grains. On the other hand, North and East Africa, the Middle East, India, West Australia and Mexico would be warmer and enabling them to produce more grain. Rice growing season as well as the area under rice cultivation could increase. However this may not happen as higher surface temperature will increase the evaporation of water, thus reducing grain yield.
                                            According to an estimate, if all the ice on the earth should melt 200 feet of water would be added to surface of all oceans, and low lying coastal cities as Bangkok and Venice would be inundated. Rise in sea level of 50 to 100 cm caused by Ocean warming would flood low lying lands in Bangladesh and West Bengal. Due to greenhouse effect, there may occur more hurricanes and cyclones and early snow melts in mountains causing more floods during monsoon. According to some, within next 25 years or so, there will be a rise in sea level by 1.5 to 3.5 metres and in Bangladesh alone 15 million people will have to move or drown.
                                                                            The UNEP has appropriately chosen the slogan "Global Warming: Global Warming" to alert the people on World Environment Day, June 5, 1989.

Global warming and climate change

As a result of increasing human population and impact of its activities on natural resources, Earth's environment has been undergoing significant changes, especially during 20th century. One of the most significant changes brought about by human activities is an increase in the concentration of carbon dioxide and other greenhouse gases in the atmosphere.

Greenhouse effect

Greenhouse or glass house is an enclosure of glasses in which tropical plants are grown during winters in areas of colder climate. Heat trapped by the glass keeps the temperature inside the greenhouse much higher than the surrounding atmosphere. A similar heating phenomenon occurs in the atmosphere also under normal conditions with normal concentration of carbon dioxide and other greenhouse gases, and hence the name greenhouse effect given. The temperature at the earth surface is maintained by the energy balance of the sun rays that strike the earth and heat that is radiated back into space and this is known as heat balance.

How greenhouse effect occurs in nature?

Air is a mixture of several gases like carbon dioxide oxygen water vapour and other gases. A blanket of air around the earth is called as atmosphere. Earth receives heat from the sun during day While some of the heat is reflected into the space during night.

The water vapour, carbon dioxide and methane form a blanket of gases that does not allow the solar radiation to escape back into the space. This blanket functions like the glass panels of a Greenhouse or Windows of a motor car which allows the sunlight to pass through but prevents the heat from being Re-radiated in outer space. This results in to warming of the Earth surface. This is  so-called greenhouse effect. This natural greenhouse effect is essential to maintain the temperature of earth at a normal habitable level.

      Besides carbon dioxide, Methane and water vapours, nitrous oxide and chlorofluorocarbons also aborbs solar radiation. These five  gases are called major Greenhouse gas is because they act like a blanket spread over the Earth surface helping it to keep warm. The major greenhouse gases includes

* carbon dioxide

* methane

* water vapour

* nitrous oxide

* chlorofluorocarbons

These gases occur in minute quantities in the atmosphere but play a critical role in maintaining even temperature on earth. Carbon dioxide contributes about 50% of total warming whereas Methane, chlorofluorocarbon and nitrous oxide 20% and 40% and 6% respectively. Besides these major greenhouse gases, hydrochlorofluorocarbons, chlorofluorocarbons, halogen, carbon tetrachloride and Ozone also called as greenhouse effect. The relative contribution of different sources to greenhouse gases is as follows:

Burning of fossil fuels --- 49%

Agriculture ---- 13%

Deforestation ----- 14%

Industrial process ------ 24%

Human activity has been making the blanket of greenhouse gases thicker,  resulting in enhanced greenhouse effect. The thicker blanket due to increasing concentration of greenhouse gases had disturbed the Global climate system. There is global warming due to enhancement of greenhouse effect all over the world.

           By 1995, it became evident that the main culprit was carbon dioxide emissions produced by the burning of fossil fuels - coal, gas and oil, in factories, power stations and cars. When we burn coal, firewood and natural gas, huge amount of carbon dioxide escape to the atmosphere. Basic activities like cattle raising and paddy planting also emit Methane, nitrous oxide and other greenhouse gases. If emissions continue to grow at current rates it is almost certain that atmospheric level of carbon dioxide will double from pre-industrial levels during the current century and it is quite possible that levels will triple by the year 2100.

Consequences of global warming and climate change

As a result of this continuous increase in levels of greenhouse gases, earth has been suffering from fever, and we have to act sincerely to cure it. Climate change has become one of the prime issue threatening the sustainability of World Environment. Besides environment, climate change has also impact on livability health and economy of the globe.

* Rise in global temperature causes sea levels to rise as polar ice caps and glaciers begin to melt, along with thermal expansion of water.

* More droughts and floods

* More terrible storms

* Many more hot days

* More diseases like malaria and dengue.

* Impacts on ecosystem would change the crop production potential of a region, especially in Asia, Africa and South and Central America.

* There will be a drastic change in  weather patterns bringing more floods or droughts in some areas.

* Forests may disappear.

* Biological diversity may reduce some species could become extinct

* Billions of people will be affected by problems of drinking water supply, sanitation and draught.

Chipko Movement

Dear friends today we are going to remember the movement which shook the minds of peoples regarding environmental protection.

Chipko movement was born in a small hilly village of the upper reaches of Himalayas. The illiterate tribal women commenced this unique moment in December 1972 that became famous as the Chipko Movement. The movement commenced in the Tehri Garhwal district of UP, that actually gathered Momentum in 1978 when the woman faced police firing. It looked as if the movement aimed at saving trees on the Himalayan slopes from the axes of greedy contractors but its objective were broad-based. It questioned the development based on the ruthless butchery of nature to achieve short term gain. It challenged the  old belief that forest mean only Timber, and emphasized their role in making soil, water and pure air which are the basis of life. it was this philosophy which popularised this Movement in many countries. The women of Advani village in Tehri Garhwal had tied the sacred thread around trees, actually hugged the trees, faced police firing in February 1978 and later courted arrest. The movement continued under the leadership of Shri Sunderlal Bahuguna in various villages like Advani and Budhekar of Tehri Garhwal. Mr Bahuguna presented the plan of this movement for protection of soil and water through ban on tree - felling in the Himalayas at the UNEP meeting held in London in June 1982.

" Every standing green tree in the forest is Sentry to protect us from avalanches and landslides, to save our soil and conserve our water. Important gift of tree to us is not Timber, but soil, water and oxygen."

           The Chipko's plan is infact a slogan of planting five Fs - food, fodder, fuel, fibre and fertiliser trees to make communities self sufficient in all their basic needs. It should generate a decentralized 

, self renewing and long-term prosperity. It will protect the environment and bring permanent peace, prosperity and happiness to mankind. Mr Bahuguna along with a team of dedicated workers later under two markers of 300 kilometre from Srinagar to Siliguri. This movement widely spread in different parts of country. Not only this, people from many other countries as France, Germany, Sweden, Switzerland etc. have visited Mr Bahuguna to have accounts and experience of his marches in different parts of the country. In an exhibition, organised on June 5 in Stockholm to mark the World Environment Day, following was written about Chipko Movement:

" A powerful environmental movement has grown up on the slopes of mountains of Himalayas. Villages have created an effective non-violent way to stop the devastation by forest industries. When the axemen comes, the people form ring around the trees - they embrace the trees. This has given the moment its name Chipko Aandolan - 2the tree hugging movement."

खासियत

रत्नापूर नगराचा राजपुत्र अमृत सेन याचं आपल्या प्रजेवर अतोनात प्रेम होतं. तो आपल्या प्रजाजनांच्या मताचा आदर करत असे, त्यामुळे तो अत्यंत लोकप्रिय होता. क्वचित कधीतरी रात्रीच्यावेळी वेषांतर करून तो आपल्या नगरातून फेरफटका मारीत असे. असाच एकदा तो वेषांतर करून फिरत असताना गावाच्या वेशीबाहेर त्याने तीन परक्या माणसांना आपापसात बोलत असताना पाहिलं.

अमृत सेन त्यांच्याजवळ जाऊन म्हणाला,  "तुम्ही कोण आहात?"

त्यावर ते म्हणाले, "आम्ही कश्यप ऋषींचे शिष्य आहोत. आम्ही 14 वर्षे त्यांच्याकडे राहून काही खास विद्या प्राप्त केल्या आहेत. आम्ही या राज्यात प्रथमच येत आहोत."

त्यानंतर पहिला म्हणाला, " मी जमिनीवर पाय आपटून जमिनीच्या पोटात काही दडलेलं असेल तर सांगू शकतो."

त्यावर दुसरा म्हणाला, " मी जमिनीच्या पोटातील खजिना नक्की कुठे दडलेला आहे हे सांगू शकतो."

तिसरा म्हणाला, " मी एखाद्या व्यक्तीला जर केवळ एकदा पाहिलं, तर नंतर ती व्यक्ती कोणताही वेश धारण करून माझ्या समोर आली, तरी मी तिला लगेच ओळखू शकतो."

मग त्या तिघांनी अमृतसरला विचारलं, "तू कोण आहेस?"

अमृत सेन म्हणाला,  "मी आहे एक सामान्य नागरिक पण माझ्याकडे सुद्धा एक गुण आहे."

"तो कुठला?" तिघे एकदमच म्हणाले.

" कोणत्याही व्यक्तीची कोणत्याही संकटातून मी सुटका करू शकतो."

" पण ही विद्या तू शिकला तरी कुठे? तूझे गुरु तरी कोण?"

राजपुत्र म्हणाला, " मला ही विद्या जन्मजातच अवगत आहे मी ही कोणाकडूनही शिकलेलो नाही".

आता त्या तिघांच्या अंगच्या त्या खास गुणांची परीक्षा घेऊन पहायची राजपुत्र अमृत सेनला इच्छा झाली.

ते सर्वजण चालू लागले. चालता-चालता पहिला माणूस रस्त्यात थांबला आणि एका विशिष्ट जागी पाय आपटून म्हणाला, " या ठिकाणी भुयारी मार्ग आहे."

मग सर्वांनी मिळून तिथे जाण्यास सुरुवात केली. खरोखरच या ठिकाणी एक भुयार होतं.  या भुयारातून चालू लागले. भुयारी रस्ता राजाच्या राजवाड्यात जात होता. थोडे अंतर चालून गेल्यावर दुसऱ्याने अचानक एका कोपऱ्यात बोट दाखवले आणि म्हणाला या ठिकाणी गुप्त खजिना आहे.

हे ऐकून राजपुत्र अमृत सेन आश्चर्याने थक्क झाला. तो त्या तिघांकडे बघुन म्हणाला, " तुम्ही इथेच थांबा. मी जरा जाऊन येतो. कदाचित आपण सर्वजण चोर आहोत, असा कोणाचा तरी गैरसमज होऊन बसेल. मी बाहेर पडून पाहून येतो आणि लगेच तुम्हाला येऊन भेटतो."

त्यानंतर तो त्या भूयारा बाहेर पडला आणि त्याने आपल्या शिपायांना बोलावून घेऊन भुयारात उभ्या असलेल्या तिघा माणसांना अटक करण्याची आज्ञा केली. त्यानंतर तो आपल्या राजवाड्याकडे निघून गेला.

दुसर्‍या दिवशी सकाळी त्या तिघा माणसांना दरबारात हजर करण्यात आले. त्या तिघांनी समोर पाहिले तर राजाच्या शेजारच्या सिंहासनावर कालचा तो माणूस बसलेला होता. तो खुद्द राजपुत्र आहे हे पाहून त्यांना धक्का बसला.

हे तिघे अनोळखी वाटसरु राजवाड्याच्या गुप्त खजिन्याच्या जवळपास सापडले, त्यामुळे त्यांना कडक शिक्षा व्हावी अशी राजांनी आज्ञा केली. त्या तिघांनी चोरट्या मार्गाने राजवाड्यात शिरून खजिना लुटण्याचा प्रयत्न केल्याचा आरोप त्यांच्यावर ठेवण्यात आला. परंतु राजा त्यांना सजा ठोठावणार इतक्यात राजपुत्र अमृतसेन त्यांनी हस्तक्षेप केला. तो म्हणाला, "महाराज, हे तिघे चोर नाहीत. उलट खास विद्या अवगत असलेली ही माणसं आहेत. तेव्हा तुम्ही त्यांना सोडावं. त्यांच्या निरपराधी तत्त्वाची ग्वाही मी देतो."

अशाप्रकारे अत्यंत कठीण परिस्थितीतून त्या तिघांची यशस्वीरित्या सुटका करून राजपुत्र अमृत सेनेने आपल्या अंशी खासियत सिद्ध केली.

      (सुधा मूर्ती, अध्यक्षा, इन्फोसिस फाउंडेशन)

Metallurgy

✓physical properties of metals

✓chemical properties of metals

✓physical properties of nonmetals

✓chemical properties of nonmetals

✓reactivity series of metals

✓ ionic compounds and their physical properties

Earth was born about 4.5 billion years ago. Various formative processes have been taking place in the core of the earth and its surroundings since its creation till today. These have resulted in the formation of various ores liquids and gases.

         In the beginning, elements were classified in accordance with their chemical and physical properties into the types of metals, nonmetals and metalloids. This classification of elements is used even today. We are going to get more information about them.

Physical properties of metals

1. Metals are generally found in solid state ( except Mercury and gallium which exist in liquid state at room temperature)

2. Metals have a luster.

3. Metals are good conductors of heat and electricity.

4. Metals have high melting and boiling points.

5. Metals can be beaten into a thin sheet. This property is called as malleability.

6. Metals can be drawn into their thin wires. This property is called as ductility.

7. Metals are sonorous.

Physical properties of nonmetals

1. Under ordinary conditions, non-metals may be solids or gases. (exception bromine is in liquid state)

2. Non metals do not have metallic lustre.  (exception iodine and diamond)

3. Non metals are not ductile and malleable.

4. Non metals are bad conductor of heat and electricity. (Graphite is a good conductor of electricity though it is non metal)

5. The melting and boiling points of nonmetals are low.

Chemical properties of metals

Metals are reactive. They have one, two or three electrons in their valence shell so they easily lose electrons and become positively charged ions. That's why metals are called electropositive elements.

Reactions of metals

a. Reaction of metals with oxygen

                          Metals combine with oxygen on heating in air and metal oxides are formed.

Metal + Oxygen =>  Metal oxide

1. When sodium metal is exposed to air it readily combines to form sodium oxide.

              Na + O2       =>        Na2O

2. when magnesium is burnt in air forms magnesium oxide.

               Mg + O2     =>         MgO

b. Reaction of metals with water

1. Reaction with Na and K

Sodium and potassium metal react rapidly and vigorously with water and liberate hydrogen gas. This is an exothermic reaction.

2Na + H2O  =>  2NaOH +  H2  +  Heat

2K + H2O   =>    2KOH   +   H2 + Heat

2. Reaction with calcium

Calcium reacts with water slowly and less vigorously.

2Ca + 2H2O  => 2Ca(OH)2 + HEAT

3. Aluminium, iron and Zinc do not react with cold or hot water but they react with steam to form their corresponding oxide. Hydrogen gas is liberated in the reaction.

2Al + 3H2O    =>  Al2O3 + 3H2

3Fe + 4H2O      =>   Fe3O4 + 4H2

Zn + H2O        =>    ZnO + H2

c.  Reaction of metals with acids 

Most of the metals react with acids to form their corresponding salt and hydrogen gas is liberated.

When the metals like aluminium, magnesium, iron or zinc are reacted with dilute sulphuric acid or hydrochloric acid, sulphate or chloride salt of metals are formed. Hydrogen gas is liberated in this reaction. The reactivity of metal can be represented as follows

         Mg > Al > Zn > Fe

Mg + 2HCl     =>     MgCl2 + H2

2Al + 6HCl     =>   2AlCl3 + 3H2

Fe  + 2HCl      =>    FeCl3 + H2

Zn + 2HCl.     =>     ZnCl2 + H2

d. Reaction of metals with nitric acid

When copper is treated with concentrated and dilute nitric acid gives different products.

Nitric acid reacts with copper according to the reaction: ...

 4 HNO₃(l) + Cu(s) ==> Cu(NO₃)₂(s) + 2 NO₂(g) + 2 H₂O(l) The copper nitrate salt that forms is a deep blue color. The nitrogen dioxide is a maroon vapor.

e. Reaction of metals with salt of other metals

When iron is reacted with copper sulphate solution iron displaces copper from copper sulphate solution. 

       Fe + CuSO4 ==> FeSO4 + Cu

In this reaction the deep blue colour of copper sulphate solution turns green due to formation of ferrous sulphate.

Reactivity series of metals

The reactivity of all the metals is not same. the arrangement of metals in the increasing or decreasing order of reactivity is called the reactivity series of metals.

According to the reactivity, metals are divided into the following groups.

1. Highly reactive metals

(Potassium, sodium, lithium, calcium)

2. Moderately reactive metals

(Magnesium, aluminium, iron, lead)

3. Less reactive metals

(Copper, Mercury, silver)

f) Reaction of metals with nonmetals

When metal is reacted with non metal the ionic compound is formed.

Example: 

When sodium is reacted with chlorine forms sodium chloride.

2Na + Cl2.    ==> 2NaCl

In this example, sodium chloride ( ionic compound) is formed because sodium loses one electron while chlorine accept one electron.

Chemical properties of nonmetals

Non metals are called as electronegative elements because they form negatively charged ions by accepting electrons.

1. Reaction of non metals with             oxygen

Non metals combine with oxygen to form their corresponding oxides. Generally oxides of nonmetals are acidic in nature but in some cases neutral oxides are also formed.

C + O2 ==> CO2 (acidic)

S + O2 ==> SO2 (acidic)

2C + O2 ==> 2CO (neutral)

2. Reaction of non metals with water

Generally non metals do not react with water (exception halogens).

Chlorine dissolves in water to give hypochlorous acid (HOCl)

Cl2 + H2O ==> HOCl +HCl

3. Reaction of dilute acid with non metals

Generally non metals do not react with dilute acids (exception halogens).

Chlorine reacts with dilute hydrochloric acid to form bromine and HCl

Cl2 + 2HBr ===> 2HCl + Br2

4. Reaction of non metals with hydrogen

Non metals react with hydrogen under certain conditions like temperature pressure and use of catalyst.

S + H2 ==> H2S (hydrogen sulphide)

N2 + 3H2 ===> NH3 (ammonia)

Ionic compounds :

        Compounds formed from cation and anion are called as ionic compounds.

The cation and anion being  positively charged, there is an electrostatic force of attraction between them. This force of attraction between cation and anion is called as the ionic bond.

General properties of ionic compounds

1. Ionic compounds are crystalline solids have a definite shape.

2. They exist in solid state and are hard.

3. they are brittle and can be broken into pieces by applying pressure.

4. They have high melting and boiling points.

5. They are soluble in water but insoluble in organic solvents like kerosene and petrol.

6. They conduct electricity in the molten state and also in an aqueous solution.

[ Generally the ionic compounds have high melting point due to following reasons:-

 1. Ionic compounds are hard due to strong electrostatic force of attraction between oppositely charged ions.

2. Due to very strong electrostatic force of attraction the cations and anions are held tightly together.

3. So large amount of energy is required to overcome this strong electrostatic force of attraction.]