Test: Air, Water And Weather - 1 - Class 5 MCQ

• The layer of the atmosphere where all weather changes take place is called the troposphere. This layer is the closest to the Earth's surface and extends up to about 15 kilometers above us.
• It contains the right amount of air for us to breathe and helps in creating different weather patterns like rain, wind, and clouds.
• So, the correct answer is the troposphere.

• The stratosphere in the atmosphere helps by absorbing harmful ultraviolet rays from the sun.
• This absorption is important because it prevents these rays from reaching us on the Earth's surface, which could otherwise harm living things.
• So, the stratosphere acts like a shield, protecting us from these dangerous rays.

• The layer of the atmosphere directly above the mesosphere is called the thermosphere.
• It is where space shuttles revolve and the temperature can increase significantly with altitude. 

• Air exerts pressure, which means it pushes on things around it.
• For example, the wind from a fan is caused by air pressure pushing the air towards you.
• So, air exerts pressure and pushes things.

Correct Answer (d)

• Hot water heats the air inside the bottle.
• The heated air expands.
• This expansion pushes air into the balloon.
• As a result, the balloon's size increases.

Thus, hot water causes the air to expand, making the balloon bigger.

• The gas that makes up about 78% of the air is nitrogen.
• Nitrogen is a colorless, odorless gas that is the most abundant in the Earth's atmosphere.
• Other gases in the air include oxygen (21%) and carbon dioxide, along with small amounts of other gases like argon.
• Nitrogen is essential for many processes, although it is not directly used by humans for breathing.

• Air pushes on things in all directions. It can push things down, up, and from the sides.
• That's why we feel air pushing on us when it's windy or when we blow up a balloon.

• Sedimentation is a process where insoluble particles settle due to gravity.
• When left undisturbed, solid particles settle at the bottom.
• Larger and denser particles settle faster, while smaller and lighter ones take longer.
• The process depends on the size, shape, density of particles and the viscosity of the liquid.

In short, sedimentation separates suspended particles by letting them settle naturally.

• Chlorination kills harmful bacteria and viruses, making water safe for drinking (True).
• Distillation separates liquids by boiling points, while chlorination adds chlorine, so this is false.
• Boiling water for 1 minute is enough to kill pathogens, but 10 minutes ensures complete safety (True).
• Potassium permanganate can also disinfect water, though less common than chlorine (True).

Correct answer: (i), (iii), and (iv).

In evaporation, water is heated to boil, and the liquid turns into vapour, leaving dissolved impurities behind. This method is often used to obtain salt from seawater.