HOTS Questions: Air around Us | Class 6: Additional Practice PDF Download

Q1: Sky appears blue. Why?
Ans: The sky looks blue because of something called "scattering." When sunlight enters Earth's atmosphere, it contains different colors. Blue light has a shorter wavelength, and tiny particles in the air scatter this blue light in all directions. Since blue light is scattered more, we see the sky as blue during the day.

Q2: Your father wears a mask over his nose while going to the office. Did you ever ask your father why he does that?
Ans: Wearing a mask over the nose helps keep away germs and diseases. Masks stop tiny drops that can carry germs from getting into the air and spreading. When your father wears a mask, he's trying to stay healthy and keep others around him safe from sickness.

Q3: If you add mud to water, you observe bubbles in water. Why?
Ans: When mud goes into water, it brings air and gases with it. The tiny air bubbles get stuck in the water and rise to the top. This makes the water look bubbly. The air in the mud and the water mixes to create the bubbles we see.

Q4: How could fish live in water?
Ans: Fish can live in water because they have special body parts. They use gills to breathe in water. These gills help them take oxygen from water. Fish also have a swim bladder that helps them float and move up or down in water. Their fins help them steer and swim, and their scales protect their bodies.

Q5: Why do mountaineers carry Oxygen cylinders with them while climbing high mountains?
Ans: Mountaineers carry oxygen cylinders because the air gets thin on high mountains. There's less oxygen at high places, and this can make people feel sick or tired. The oxygen cylinders give them extra oxygen to breathe so they can climb without getting sick.

Q6: What is air made up of? Describe its composition and the percentage of its major components.
Ans: Air is a mixture of different gases. The composition of air includes mainly nitrogen, oxygen, carbon dioxide, and traces of other gases. Nitrogen makes up about 78% of the air, while oxygen constitutes around 21%. Carbon dioxide is present in a small amount, about 0.04%. Other gases like argon, neon, and helium are present in very small quantities.

Q7: Explain the concept of air pressure. How does it vary with altitude?
Ans: Air pressure is the force exerted by the weight of the air above us on a unit area of the Earth's surface. The air pressure is higher at the surface and decreases as we go higher in the atmosphere. This is because there is more air above us at the surface, resulting in higher pressure. As we move up, the air becomes thinner, and thus, the pressure decreases. This is why it becomes harder to breathe at high altitudes.

Q8: Why do we feel the pressure of air on our bodies? Describe an experiment to demonstrate air pressure.
Ans: We feel the pressure of air on our bodies because the air molecules are in constant motion and exert force in all directions. An experiment to demonstrate air pressure can be done using a suction cup. When a suction cup is pressed against a surface, the air is removed from within the cup, creating a vacuum. The higher air pressure outside the cup holds it firmly against the surface, showing the effect of air pressure.

Q9: Explain the concept of buoyancy with respect to air. Why do objects appear lighter in air compared to water?
Ans: Buoyancy is the upward force exerted by a fluid on an object placed in it. In air, objects appear lighter compared to water because air is less dense than water. The buoyant force depends on the density of the fluid. Since air is less dense, the buoyant force on an object in air is weaker than in water, making the object seem lighter.

Q10: How does air help in the process of pollination? Explain with an example.
Ans: Air plays a crucial role in the process of pollination for plants that depend on wind pollination. In wind pollination, flowers produce light and feathery pollen grains that are carried by the wind to other flowers for fertilization. An example is the pollen from male flowers of maize plants being carried by the wind to the female flowers, allowing fertilization to occur. The light and small pollen grains are easily carried by the air, facilitating the pollination process.