Arihant Class 10 NCERT Science Exemplar Problems + Solutions

244 NCERT Exemplar (Class X) Solutions Long Answer Type Questions Q. 32 In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category. Ans. In the context of natural resources, the following terms refer to Reduce This means to use a material/commodity in lesser quantity. Recycle Means a material that is used once, is collected and sent back to a manufacturer so that they can make some other useful materials from it. Reuse It means using a thing over and over again instead of throwing it away. This is actually even better than recycling because the process of recycling uses some energy. From among the materials we use in daily life, we can reduce electricity use by switching off unnecessary lights and fans and save water by repairing leaky taps. Recycle used paper, plastic bottles, metal objects can be recycled. Reuse The plastic bottles in which we buy various food-items like jam or pickle can be reused for storing things in kitchen, the used envelopes can be reused to store things, reversed inside out to be used again. Q. 33 Prepare a list of five activities that you perform daily in which natural resource can be conserved or energy utilisation can be minimised. Ans. Activities that we perform daily in which natural resources cab be conserved or energy utilisation can be minimised are (i) Use fan and light only when required. Switch them off in unoccupied rooms. (ii) Use CFL in place of conventional bulbs/tubes. (iii) Avoid using a hose pipe for watering plants as a lot of water is wasted through it. (iv) Use solar energy whenever possible. (v) Unused water in the water bottles may be used for watering plants. (vi) Close taps when not in use. (vii) Use public transport or car pools to save fuel. (viii) Use CNG as in alternative fuel. (ix) Pressure cookers should be used for cooking food to save fuels like LPG. (x) Use stairs to climb atleast upto three floors of building instead of taking lift. This will save electricity (any five). Q. 34 Is water conservation necessary? Give reasons. Ans. Conservation of water is necessary due to following reasons (i) Uneven distribution Some parts of our country have high resources of water whereas other parts suffer from chronic water shortage. (ii) Wide seasonal as well as yearly fluctuation in rainfalls. (iii) Water in rivers and ponds is polluted by dumping of untreated sewage and industrial wastes into it. (iv) The changing life style of people, especially in urban areas, is consuming more water. (v) High yielding varieties of crop uses much more water for irrigation. Also insufficient vegetation cover on ground allow little water to seep in and gets stored as ground water.

Management of Natural Resources 245 Q. 35 Suggest a few useful ways of utilising waste water. Ans. Some usefull ways of utilising waste water are as follows (i) For recharging the ground water. (ii) For irrigation. (iii) Treated municipal water can be used for washing cars, watering gardens etc. (iv) Waste water from the kitchen can be collected and reused in toilet flushing. (v) Certain pollutants in municipal water can become fertiliser for various crops. Q. 36 What is the importance of forest as a resource? Ans. Forest are renewable natural resource. They are important as a resource due to following reasons (i) Provide habitat, food and protection to wildlife. (ii) Help in balancing CO2 and O2 of atmosphere. (iii) Improves water holding capacity of soil. (iv) Regulates water cycle. (v) For human beings, they are the source of various essential commodities like fuel, wood, timber, fruits, resins, etc. (vi) Forest helps in conservation of biodiversity as a large number of species (of plants and animals) live inside them. Q. 37 Why are the Arabari forests of Bengal known to be a good example of conserved forest? Ans. The Arabari forest of Bengal were badly degraded. Then in 1972, the West Bengal Forest Department planned to revive the degraded forest by involving the local people. The villagers of the surrounding area were involved in the protection of 1272 hectares of this forest. With the active participation of local people living around the forest, the degraded sal forest of Arabari became thick and green within ten years. In return, the villagers were given employment in both silviculture and harvesting operations of the forest and allowed to collect firewood and fodder from the forest area on a nominal payment. Thus, the Arabari forest provides a good example of conserved forest.