Olympiad Test: Our Environment - 1 - Class 6 MCQ

Air is used in all the options except for boiling water:

• Winnowing: Air is used to separate lighter particles (like chaff) from heavier grains.
• Inflating tyres: Air is used to fill tyres to provide them with the necessary pressure.
• Filling balloons: Air or helium is used to fill balloons to make them float or simply inflate them.

However, boiling water does not involve air as part of the process. The process of boiling involves heating water until it reaches its boiling point, and air does not play a direct role in this.

During rain, soil animals like earthworms come out of their burrows primarily for respiration. The burrows tend to fill with water during rainfall, reducing the oxygen available in the soil. As a result, these animals come to the surface where the oxygen level is higher, making it easier for them to breathe.

Options like decomposition, nutrition, and regeneration are not the primary reasons for soil animals coming out during rain.

The balance between carbon dioxide and oxygen is maintained by photosynthesis and respiration in which carbon dioxide and oxygen is used and oxygen and carbon dioxide is produced respectively.

When gases like sulphur dioxide and nitrogen dioxide mix with water vapour present in th e air, th e y form H₂SO₄ and HNO₃. T h ese acids mix with the rain and fall on the ground as acid rain. Acid rain is very harmful for living beings, buildings, monuments, etc. Acid rain does not cause any damage to the ozone layer as ozone layer is present in the stratosphere and all weather related changes like rain, cloud formation, etc., occur in the troposphere.

For a wet cloth to dry fast, it has to be a sunny day and the temperature must be high. During sunny days, the humidity in the air will be less. So wet clothes will dry faster. A rainy day with higher temperature is slightly better at drying than with lower temperature. A rainy day will make the clothes wetter.

The flowchart helps us identify three gases, X, Y, and Z, based on their properties. Let’s analyze step by step:

1. Supports burning:

   • The gas in the air that supports burning is oxygen (O₂).
   • Therefore, X = O₂.

2. A greenhouse gas leading to global warming:

   • The greenhouse gas in the air is carbon dioxide (CO₂).
   • Therefore, Y = CO₂.

3. An inert gas:

   • An inert gas (non-reactive gas) in the air is helium (He).
   • Therefore, Z = He.

Final answer:

From the options given:

• X = O₂, Y = CO₂, Z = He matches option A.

Thus, the correct answer is A.

The method in which earthworms are added to a pit to accelerate the process of decomposition is called vermicomposting. Earthworms help break down organic matter into nutrient-rich compost, which can be used to improve soil quality.

The heat of the sun causes evaporation of water from water bodies. Trees and plants give out water vapour through their leaves. This is called transpiration. The cool air causes the water vapour to condense into clouds. Precipitation means rainfall, snowfall, ice or sleet from the clouds towards the earth.

In the given flow chart, P could be liquid or solid, Q could be oxygen, R could be CO₂ and S could be n itroge n. N itrog en is a gas that is not produced during respiration.

The atmospheric pressure is measured with the help of barometer. Places near the water bodies like sea are expected to be more humid than the places that are far away.