Explanation

• The ozone layer is a layer of gas in the stratosphere that contains a high concentration of ozone (O3).
• It absorbs most of the sun's ultraviolet (UV) radiation, protecting the Earth from harmful UV rays.

Explanation

Hydrogen and helium are the two lightest gases, both significantly lighter than air. 

Hydrogen: Considered the lightest gas.

Helium: Also lighter than air, but twice as heavy as hydrogen.

Air: Has a higher molecular weight than both hydrogen and helium. 

Explanation

Atmosphere is divided into Five layers/parts:

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere

Explanation

Open garbage dumps release toxic gases into the air, leading to air pollution (e.g., methane, ammonia).

When rainwater passes through waste, it forms leachate, which contaminates groundwater and causes water pollution.

Explanation

Fossil fuels (like coal, oil, and natural gas) are non-renewable because they take millions of years to form.

Once used, they cannot be replenished on a human timescale.

Explanation

Temperature: High during the day (often above 35°C or 95°F), cooler at night.

Rainfall: Very low, usually less than 250 mm (10 inches) per year.

Humidity: Low, making the air feel dry.

Examples: Sahara Desert (Africa), Arabian Desert (Middle East), parts of Arizona and Nevada (USA).

Vegetation is sparse, and plants/animals are adapted to conserve water.

Explanation

Sustainable development means meeting the needs of the present without compromising the ability of future generations to meet their own needs.

This definition is from the World Commission on Environment and Development (Brundtland Report).

Explanation

The atmosphere is the gaseous layer that surrounds the Earth.

It is composed mainly of nitrogen, oxygen, and trace gases.

It plays a crucial role in protecting life on Earth by filtering harmful radiation and regulating temperature.

Explanation

The migration of people from rural to urban areas increases the demand for housing, often outstripping supply.

This rapid urbanization leads to overcrowding and a shortage of affordable housing in big cities.

Explanation