Air and Atmosphere Test - 1

Wax does not burn with a flame. Wax is used to make candles. The material that burns is the thread and wax helps it to burn slowly.

The air that we breathe out contains carbon dioxide gas. When carbon dioxide gas comes in contact with lime water it turns lime water milky. Therefore, the correct answer is A.

Volcanic eruption is a natural phenomenon and is not a result of human activities. Oxides of sulphur and nitrogen are released in a volcanic eruption.

The correct answer is C.

Why alternative A is wrong:

Refrigerators and air-conditioners release CFCs, which are responsible for both global warming and depletion of ozone layer. These are man-made substances.

Why alternative B is wrong:

Most of the vehicles run on fossil fuels. These fuels on burning release harmful gases.

Why alternative D is wrong:

Most of the factories release a lot of smoke into the atmosphere. Smoke contains unburnt carbon particles and other harmful gases that pollute the environment.

Acid rain is composed of nitric acid and sulphuric acid. It causes corrosion of materials like marbles, metals etc.

Yacht is a type of boat that has a vertical flag and a mast. Moving air exerts a force on the mast along its direction. As a result, the yacht sails on the river in the direction of the moving air. Thus, the of source of energy that helps in the movement of the yacht is the moving air called wind energy.

Lead present in fuel leads to the formation of harmful compounds on combustion. As a result, petrol containing lead was banned sometime ago. Unleaded petrol is relatively a cleaner fuel.

The correct answer is B.

Why alternative A is wrong:

Volcanic eruption leads to the formation of oxides of sulphur and nitrogen. These gases cause acid rains.

Why alternative C is wrong:

Leaking refrigerators release chlorofluorocarbons (CFCs), which cause greenhouse effect and depletion of ozone layer.

Why alternative D is wrong:

The process of extraction of metals produces many pollutants. For example, the extraction of metals from minerals containing sulphides releases oxides of sulphur.

Dust comprises tiny, solid particles that are always present in air. As we inhale air, dust particles enter the nose. Fine hair and mucus present in the nostrils trap these dust particles and prevent them from entering the lungs.

When iron gets oxidized in the presence of moisture, a reddish-brown layer gets deposited on the surface of the metal. This condition is known as rusting of iron.

Carbon dioxide is used by green plants to make food in the presence of sunlight. Living organisms consume oxygen and release carbon dioxide during respiration. When an object burns in the presence of oxygen, carbon dioxide gas is released.

For combustion to take place, essential conditions include the presence of a fuel, oxygen and heat.