Class 5 Science - Air and Water - HOTS Questions

Q1: Which of the following scenarios illustrates the process of condensation?
(a) Filling a glass with cold water on a hot summer day.
(b) Rainwater evaporating from a puddle on a sunny day.
(c) Water droplets forming on the outside of a cold drink glass.
(d) A river flowing rapidly after heavy rainfall.
Ans: (c)
Condensation occurs when water vapor in the air cools down and changes into tiny water droplets, forming visible moisture on a surface. In this situation, the cold drink glass cools the surrounding air, causing the water vapor in the air to condense and form droplets on the glass surface.

Q2: During the process of photosynthesis, what role does air play in the presence of water?
(a) Air provides oxygen to water, enabling plants to produce food.
(b) Air helps water evaporate from plants' leaves to cool them down.
(c) Air allows water to flow freely in the soil, reaching plant roots.
(d) Air combines with water to produce carbon dioxide for plant growth.
Ans: (a)
During photosynthesis, plants use carbon dioxide from the air and water from the soil to produce glucose (food) and oxygen. The air provides the essential carbon dioxide, while water provides hydrogen during this process.

Q3: Why is it essential to keep water sources clean and unpolluted?
(a) Polluted water leads to excessive evaporation, causing water shortages.
(b) Pollutants in water decrease the level of oxygen in the atmosphere.
(c) Polluted water can cause respiratory problems due to contaminated air.
(d) Clean water is essential for maintaining a balanced ecosystem and human health.
Ans: (d)
Clean and unpolluted water is crucial for supporting aquatic life and maintaining a balanced ecosystem. Additionally, human beings rely on clean water for drinking, sanitation, and various other daily needs. Pollution in water can harm both the environment and human health, making it crucial to keep water sources clean.

Q4: Which of the following statements is true regarding the water cycle?
(a) The water cycle is primarily driven by the Earth's rotation.
(b) Water always flows in a unidirectional path during the water cycle.
(c) Water in the water cycle can only change states through evaporation and precipitation.
(d) The water cycle is a continuous process where water undergoes various changes and circulates through the atmosphere, land, and oceans.
Ans: (d)
The water cycle involves continuous processes of evaporation, condensation, precipitation, and runoff. Water can change states (liquid, solid, gas) during this cycle, and it circulates through various parts of the Earth, including the atmosphere, land, and oceans.

Q5: What causes the Earth to experience different seasons?
(a) The Earth's distance from the Sun changes during different times of the year.
(b) The Earth's axis is tilted, causing different parts to receive varying amounts of sunlight.
(c) The level of air pollution varies, affecting the amount of sunlight reaching the Earth's surface.
(d) The amount of water vapor in the atmosphere fluctuates, causing temperature variations.
Ans: (b)
The Earth's axis is tilted with respect to its orbit around the Sun. This tilt results in different parts of the Earth receiving varying amounts of sunlight during different times of the year, leading to the changing seasons.

Q6: In a coastal area, during the daytime, the land heats up faster than the nearby sea. Why does this happen?
(a) The sea has a higher heat-absorbing capacity than the land.
(b) The land has a higher heat-absorbing capacity than the sea.
(c) The air above the sea is denser, preventing heat from reaching the land.
(d) The air above the land is denser, preventing heat from reaching the sea.
Ans: (b)
Land has a lower heat-absorbing capacity compared to water. During the day, the land heats up faster because it can absorb and retain heat more efficiently than the nearby sea. As a result, the air above the land gets warmer, leading to the formation of a sea breeze blowing from the cooler sea towards the warmer land.

Q7: What is a significant consequence of air pollution on water bodies?
(a) Increased fish population due to improved water quality.
(b) Acidification of water bodies, harming aquatic life.
(c) Enhanced oxygen levels, leading to algae overgrowth.
(d) Reduction in water evaporation rates, causing droughts.
Ans: (b)
Air pollution can lead to the release of pollutants such as sulfur dioxide and nitrogen oxides, which can dissolve in rainwater and make water bodies more acidic. This process is known as acid rain, and it can harm aquatic life, making the water unsuitable for many organisms.

Q8: During a heavy rainfall, why do puddles form on the ground?
(a) The ground's surface becomes impermeable during rainfall.
(b) The air pressure decreases, causing water to accumulate on the ground.
(c) Water evaporates from the soil and collects in low-lying areas.
(d) The wind direction changes, causing water to pool in certain areas.
Ans: (a)
In urban areas and places with hard surfaces like concrete and asphalt, rainwater cannot seep into the ground easily. As a result, the surface becomes impermeable, causing water to accumulate and form puddles on the ground during heavy rainfall.

Q9: How does the presence of trees and vegetation near water bodies benefit the ecosystem?
(a) Trees prevent water bodies from evaporating, reducing water loss.
(b) Vegetation releases excess water into the atmosphere, causing rainfall.
(c) Trees and vegetation act as a barrier, preventing water pollution.
(d) The roots of trees and vegetation stabilize the soil, reducing erosion and sedimentation.
Ans: (d)
Trees and vegetation play a crucial role in preventing soil erosion and sedimentation in water bodies. Their roots hold the soil together, reducing the impact of flowing water and preventing excessive sedimentation in rivers, lakes, and other water sources.

Q10: Why is it important to conserve water, even though it appears to be abundant on Earth?
(a) Water reserves are limited, and human activities consume water faster than it can be naturally replenished.
(b) The Earth's water supply is continually increasing, making conservation unnecessary.
(c) Pollution has made water an unsuitable resource for consumption and daily use.
(d) Water is only abundant in certain regions, leading to regional water scarcity.
Ans: (a)
Although the Earth's surface is covered with water, a significant portion of it is not readily available for human use (e.g., oceans and ice caps). Additionally, increasing human populations and various activities, such as agriculture and industry, consume water faster than it can be naturally replenished. As a result, it is essential to conserve water to ensure a sustainable supply for future generations and to protect natural ecosystems that depend on water resources.