Test: Air and Water - 1 - Class 3 MCQ

The burning of a fire requires a few essential components. Among these:

• Oxygen: Essential for combustion; without it, fire cannot burn.
• Other gases like carbon dioxide, nitrogen, and substances like water vapour do not support fire.

Air is a matter. It has mass.

The expansion of a balloon when air is blown into it demonstrates that:

• Air fills space - As the balloon expands, it shows that air takes up the space inside the balloon.

The atmosphere is essential for several reasons:

• Supports life: It contains gases like oxygen and carbon dioxide, which are vital for living organisms.
• Protection: It shields the Earth from meteoroids and harmful solar radiation.
• Water cycle: It plays a crucial role in the water cycle by supporting the processes of evaporation and precipitation.

The statement that the atmosphere does not help with the water cycle is incorrect.

Space shuttles orbit in the thermosphere due to several reasons:

• The thermosphere extends from about 90 km to 600 km above the Earth's surface, providing enough space for orbits.
• This layer is above the stratosphere and mesosphere, where the atmosphere is too dense for a stable orbit.
• Operating in this region minimizes the impact of atmospheric drag on the shuttle.

Nitrogen is a colourless gas with no smell.

• It makes up approximately 78% of the Earth's atmosphere.
• Essential for life, it is a part of all living cells.
• Commonly used in industries like food preservation and electronics.

The troposphere is the layer of the atmosphere where weather changes occur. This is because:

• The troposphere is the lowest layer of the atmosphere, where most weather phenomena like rain, snow, and winds happen.
• It contains the majority of the atmosphere's water vapour, which is essential for weather formation.
• Temperature and pressure changes in this layer drive weather patterns.

Other layers, such as the stratosphere, exosphere, and thermosphere, have different characteristics and do not significantly contribute to weather changes.

The ozone layer is crucial in protecting life on Earth from harmful ultraviolet (UV) rays.

• Ozone absorbs most of the sun's harmful UV radiation.
• This absorption helps prevent skin cancer and other health issues.
• It also protects ecosystems, including marine life.

Without the ozone layer, UV rays would increase, causing significant damage to living organisms.

Plants use carbon dioxide during a process called photosynthesis. Here's how it helps:

• Photosynthesis is the process by which plants make their own food.
• During this process, plants convert carbon dioxide and water into glucose and oxygen, using sunlight.
• This conversion is crucial for plant growth and energy production.

Plants primarily obtain nitrogen from the soil. Here's how it works:

• Soil contains nitrogen in forms like nitrates and ammonium, essential for plant growth.
• Plants absorb these nutrients through their roots.
• This process is crucial for forming proteins and other vital compounds.