Important questions based on NCERT syllabus for Chapter 14 - Natural Resources:
Question-1: How is rain formed?
Solution: (i) When water bodies are heated during the day, a large amount of water evaporates and goes into the air. Some amount of water vapour also gets into the atmosphere because of various biological activities.
(ii) This air also gets heated. The hot air rises up carrying the water vapor with it.
(iii) As the air rises, it expands and cools. This cooling causes the water vapor in the air to condense in the form of tiny droplets.
(iv) This condensation of water is facilitated if some particles could act as the ‘nucleuses’ for these drops to form around. Normally dust and other suspended particles in the air perform this function.
(v) Once the water droplets are formed, they grow bigger by the ‘condensation’ of these water droplets. When the drops have grown big and heavy, they fall down in the form of rain.
Question-2: Write any two sources of each:
i. Water pollution
ii. Air pollution
iii. Soil pollution
Solution: i. Water pollution - addition of domestic waste and sewage, hot water release after cooling power plants.
ii. Air pollution - burning of fossil fuel, industrial emissions.
iii. Soil pollution - dumping the soil with municipal waste, excessive use of pesticides and weedicides.
Question-3: Write a note on how forests influence the quality of our air, soil and water resources.
Solution: Influence on air:
(i) Forests balance the percentage of carbon dioxide and oxygen in the atmosphere. The increasing amount of carbon dioxide caused by human activities is balanced by a large intake of carbon dioxide by plants during the process of photosynthesis. Simultaneously, a large amount of oxygen is released.
Influence on soil:
(ii) Forests prevent soil erosion. Roots of plants bind the soil tightly in a way that the surface of the soil cannot be eroded by wind, water, etc.
Influence on water:
(iii) Forests help in the replenishment of water resources. During the process of transpiration, a huge amount of water vapour goes into the air and condenses to form clouds. These clouds cause rainfall that recharges the water bodies.