Q. If all the waste we generate is biodegradable, will this have no impact on the environment? Ans. It will have only short term impact on environment. The action of decomposers will slow down and some air/water pollution will be caused. However, in longer term, there will be no impact of biodegradable waste on the environment.
Q. List the products of combustion of fossil fuels. What are their adverse effects ? Ans. Products of combustion of fossil fuels are carbon dioxide, water, oxides of nitrogen and sulphur. When combustion takes place in insufficient air, carbon monoxide is also formed. Oxides of nitrogen and sulphur and carbon monoxide are poisonous gas. Carbon dioxide is a greenhouse gas. The layer of carbon dioxide around the earth prevents the heat rays to escape leading to global warming
Q. Why is sustainable management of natural resources necessary? Out of the two methods reuse and recycle which one would you suggest to practise and why? Answer : Sustainable management of natural resources is necessary to increase the over all life of natural resources specially non-renewable resources and also to control the environmental pollution. Both reuse and recycle are the good choices. Reuse: If we reuse something then the cost of recycle will be saved. Recycle: It is not necessary that each and everything can be reused, so after getting recycled the life of the resource will be enhanced.
Q. Why should biodegradable and non-biodegradable wastes be discarded in two separate dust bins? Answer : Biodegradable wastes can be properly recycled for future use. If biodegradable and non biodegradable wastes are discarded in the same dustbin, then the non-biodegradable waste will make the biodegradable waste unfit for recycling. It will also interfere in the process of recycling.
Q.We often observe domestic waste decomposing in the bylanes of residential colonies. Suggest ways to make people realise that the improper disposal of waste is harmful to the environment. Answer : Some of the ways to make people realize that the improper disposal of waste is harmful to the environment are: (a) Improper disposal of waste will serve as a breeding ground for mosquitoes and will create favourable conditions for the spread of various diseases. (b) Improper disposal of waste will release harmful gases in the environment. It will make the environment unclean and unhygienic for normal living of the organisms. (c) The waste will flow to water bodies along with the rain water and become a threat to aquatic organisms. Q. List and explain any two advantages associated with water harvesting at community level. Answer : Two advantages associated with water harvesting at community level are: (a) It will reduce the overexploitation of water resources. (b) It also helps in mitigation of droughts and floods. Q.List four advantages of water stored in the ground. Answer : Advantage of water stored in the ground (i) It does not evaporate and is available to wells (ii) It does not provide breeding grounds for mosquitoes etc. (iii) Provides moisture for vegetation over a wide range. (iv) It is also protected from contamination by human and animal waste.
Q."Burning fossil fuels is a cause of global warming." Justify this statement. Answer : Fossil fuels are composed of carbon, hydrogen, nitrogen and sulphur. When these are burnt, the products are CO2, H2O, oxides of nitrogen and sulphur. Incomplete combustion of fossil fuels produces green house gases such as CO2, . If huge amount of fossil fuels are burnt, it would produce high amount of CO2 resulting intense global warming.