Question

B. Choose the correct option.
1. The highest clouds are at about
a, 1 km above the surface of the earth
b, 15 km above the surface of the earth
c. 50 km above the surface of the earth
d. hundreds of kilometres above the surface of the earth

2. Which of these gases is present in the maximum amount in the atmosphere?
a. Oxygen b. Carbon dioxide c. Nitrogen d. Ozone

3. Which of these is not a property of air?
a. Air occupies space b. Air helps burning c. Air exerts pressure d. Air has no weight

4. Which of these works because of air pressure? a. Straw b. Dropper c. Doctor's syringe d. All of these

5. Which of these can be used to remove soluble impurities from water?
a. Distillation b. Filtration c. Sedimentation

6. Which of these processes is used in a town water supply to kill d. Decantation germs in water?
a. Sedimentation b. Filtration c. Boiling d. Chlorination ​

Answer 1

Explanation:

1)C)

2)C)

3)D)

4)D)

5)A)

6)D)

Answer 2

1. The highest clouds are at about

a. 1 km above the surface of the earth

b. 15 km above the surface of the earth

c. 50 km above the surface of the earth

d. hundreds of kilometres above the surface of the earth

Ans. (D) hundreds of kilometres above the surface of the earth

→ Highest clouds are located at altitudes of around 76 to 85 km (249,000 to 279,000 ft). Here, the nearest answer is 100 km.

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2. Which of these gases is present in the maximum amount in the atmosphere?

a. Oxygen

b. Carbon dioxide

c. Nitrogen

d. Ozone

Ans. (C) Nitrogen

→ Air in earth's atmosphere is made up of approximately 78 percent nitrogen.

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3. Which of these is not a property of air?

a. Air occupies space

b. Air helps burning

c. Air exerts pressure

d. Air has no weight

Ans. (D) Air has no weight.

→ Air always has mass and weight.

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4. Which of these works because of air pressure?

a. Straw

b. Dropper

c. Doctor's syringe

d. All of these

Ans. (D) All of these

→ Application of air pressure involves working of straw, dropper, doctor's syringe etc.

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5. Which of these can be used to remove soluble impurities from water?

a. Distillation

b. Filtration

c. Sedimentation

d. Decantation

Ans. (A) Distillation

→ Distillation can be used to remove soluble impurities from water. Sedimentation, filtration and Decantation are used for removing insoluble impurities from water.

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6. Which of these processes is used in a town water supply to kill germs in water?

a. Sedimentation

b. Filtration

c. Boiling

d. Chlorination

Ans. (D) Chlorination

→ Chlorine kills a large variety of microbial waterborne pathogens.

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