Lakshya Education MCQs

Question: List any five activities which are possible due to the presence of air. [5 MARKS]

: Activities : 1 Mark each

The activities which are possible due to the presence of air are:
(a) Respiration in animals and plants
(b) Sailing of boats, airplanes
(c) Burning of any substance
(d) Photosynthesis in plants
(e) Power generation from wind mills

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More Questions on This Topic :

Question 1. Choose the odd one out. Give reason for the same. [1 MARK]

rustling of leaves, flying of kite, making tea

: Making tea. Rustling of leaves and flying of kite needair whereas making of tea has nothing to do with moving air.
Question 2. Suggest three measures to prevent air pollution. [3 MARKS]

: 1Mark each

Air pollution can be prevented as follows:
(i) By using smokeless sources of energy like solar energy and electrical energy.
(ii) By using filters for the smoke coming out of the chimneys of factories and power plants.
(iii) By using internal combustion engines in vehicles for complete and efficient burning of fuel.
Question 3. What is rust? What are the two conditions of rusting? [3 MARKS]

: Definition : 1Mark
Conditions: 2 Marks

Rusting is the process in which iron slowly reacts with oxygen in the air in the presence of moisture to form a flaky brown substance called rust.
The two most important conditions of rusting are:
(i) Presence of oxygen (air)
(ii) Presence of moisture
Question 4. Air contains nitrogen and oxygen in 4:1 ratio of volumes. Prove it with an experiment. Also make a diagram depicting the same. [5 MARKS]

: Experiment : 3 Marks
Diagram : 2 Marks

Take a candle and fix it at the center of a glass container. Add some quantity of water in the glass container. Now place an empty glass jar over it. Above the water surface, mark five lines at equal distances as depicted in the diagram below.l2
Carefully light the candle and wait for a few seconds. The flame will be extinguished due to the absence of oxygen. We can observe that the water level in the glass jar is 1/5 of the volume of air present in the glass jar. The above experiment proves that one part of the air present in the glass jar supports the combustion process, i.e., oxygen. Hence, 1/5th of the volume of air is oxygen. Thus, we can conclude that air contains nitrogen and oxygen in the ratio 4:1.
Question 5. Give reasons: [3 MARKS]

a) Clothes do not dry quickly on a cloudy day.

b) It is not advisable to fill hydrogen gas in big air balloons.

c) Balloons filled with helium gas float up into the air.

: a) 1 Mark
b) 1 Mark
c) 1 Mark

a)There is a large amount of moisture in the air on a cloudy day. So, clothes do not dry quickly on a cloudy day. The rate of evaporation is higher i.e. clothes dry quicker when the air is less humid.
b)Hydrogen is a combustible gas and forms an explosive mixture with air, so it is not advisable to fill hydrogen gas in big air balloons.
c) Since air is much heavier than helium, the air pushes the light helium balloon towards higher altitudes where the air is also lighter.
Question 6. Mention five important properties of air. [5 MARKS]

: Each property :1Mark

The properties of air are as follows:
1) It is transparent.
2) It supports all life forms on Earth.
3) It is colourless.
4) It occupies space.
5) It is present everywhere - on land, in water and in soil.

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