Our Natural Resources - 1 (Class IX)

Sulphur dioxide is emitted from volcanic eruptions in large quantities.

The water cycle, also known as the hydrologic cycle or the H₂O cycle, describes the continuous movement of water on, above and below the surface of Earth. The water moves from one reservoir to another, such as from river to ocean or from ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, runoff and subsurface flow.

This is the correct option as helminths are not chemical water pollutants. They are biological water pollutants.

This is the correct answer as these statements are correct. Lichens grow on the surface of rocks and while growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil. Mosses grow on this surface and they cause the rock to break up further. Bits of decayed living organisms in the soil are called humus.

This is the correct answer. Blue-green algae, apart from rhizobium bacteria, can fix free nitrogen.

Acid rain corrodes marbles of a monument. This phenomenon is called marble cancer.

CNG is a cleaner fuel. It is being promoted in cities with high air pollution. CNG combustion produces fewer undesirable gases than the other fuels. It is safer than other fuels in the event of a spill because natural gas is lighter than air and disperses quickly when released. 

Plant roots play a role in preventing soil erosion. Soil erosion is a naturally occurring process that affects all landforms. In agriculture, soil erosion refers to the wearing away of the topsoil of a field by natural physical forces of water and wind or through forces associated with farming activities such as tillage.

Sun, water, wind and living organisms help in soil formation. Weathering describes the means by which soil, rocks and minerals are changed by physical and chemical processes into other soil components. Weathering is an integral part of soil development. Depending on the soil-forming factors in an area, weathering may proceed rapidly over a decade or slowly over millions of years. 

The Chipko Movement originated in Khejarli village (India). In 1731, Amrita Devi Bishnoi sacrificed her life to protect Khejri trees at Khejarli village in Jodhpur district of Rajasthan.

Transpiration - The process of loss of water in the vapour state from the leaves' surface especially through surface openings called stomata, is known as transpiration.  

Tawa Dam is located at the joining of Tawa river and Denwa river, in Hoshangabad district, Madhya Pradesh. It was built in 1978. It was mainly built for irrigation purpose. This dam irrigates a large area of Hoshangabad district.

Option (2) is correct. Construction of such dams displaces large number of peasants and tribals, which stay nearby. Also, poor tribals who do not get any benefits from these projects are alienated from their lands without adequate compensation. The oustees of the Tawa Dam are still fighting up for the benefits they were promised.

The moon has no atmosphere to hold in heat at night or prevent the surface from getting hot during the day.

Heat can be trapped by glass. Hence, the temperature inside a glass enclosure will be much higher than that in the surroundings. This phenomenon was used to create an enclosure where tropical plants could be kept warm during the winters in colder climates. Such enclosures are called greenhouses.