Our Natural Resources - 1 (Class IX)

Weathering causes the disintegration of rock near the surface of the earth. Plant and animal life, atmosphere and water are the major causes of weathering. Weathering breaks down and loosens the surface minerals of rock, so they can be transported away by agents of erosion such as water, wind and ice.

A renewable resource is a resource which is replaced naturally and can be used again. Examples are: oxygen, freshwater, solar energy, timber and biomass.

This is the correct option. Sun, water, wind and living organisms are the factors that help in the formation of soil.

There are two overlapping water cycles: global and smaller cycles. 

Transpiration is the evaporation of water from plant leaves. It is a part of water cycle.

The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation.

This is the correct answer. Oxygen is an essential component of most biological molecules like carbohydrates, proteins, nucleic acids and fats (or lipids). Oxygen from the atmosphere is used up in the processes of combustion and respiration, and in the formation of oxides of nitrogen.

This is the correct option as all of these are the effects of air pollution on human beings. Hydrocarbon vapours damage the internal organs and cause cancer, suspended particulate matter causes asthma, bronchitis and allergic cold, and pollutant gases cause irritation in eyes, throat and lungs along with injuring lungs, liver, kidneys, spleen and nervous system.

This is the correct option as azotobacter plays the role of nitrogen fixation in nitrogen cycle.

This is the correct option as argon is not a greenhouse gas.

This is the correct option as sewage is not a non-degradable soil pollutant. It decomposes easily.

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.

Lichens are a biological indicator of air pollution.

Conversion of nitrate into nitrogen is denitrification; conversion of ammonia into nitrites and then into nitrates is nitrification; conversion of atmospheric nitrogen into ammonia is nitrogen fixation; and conversion of organic nitrogen within the remains of plants or animals back into ammonium by bacteria or fungi is ammonification.