9. Air | EVS I | Class 4

The blog discusses the Questions and Answers from the lesson 9, Air, Environmental Science, Part 1, from Class 4. Students can use these answers for reference in their studies.

(A) Find out.

Before drawing a medicine into the syringe, why is the plunger first pressed to the bottom of the barrel ?

Ans. Before drawing a medicine into the syringe the plunger first pressed
to the bottom of the barrel, because :

1. When the plunger is pressed to the bottom all the air in the plunger is removed.

2. Now, since there is no air in the plunger the medicine can be drawn in.

3. This is done so as to avoid the mixing of impure air with the medicine.

(B) Think and tell.

1. Name some things of everyday use in which air is filled under pressure.

Ans. Tyres of bicycle, car, truck and balloons.

2. What is seen mixing with the air when wood or coal burns ?

Ans. When wood or coal burns it releases smoke that gets mixed with air. The smoke can contain harmful gases and particulate matter.

3. What gets mixed with the air when water boils ?

Ans. Water vapour gets mixed with the air when water boils.

(C) Fill in the blanks.

1. There is ………………… even in an empty container.

2. The air at a greater height from the earth is ………….. than the air nearer to the earth.

3. If all the air were divided into five parts, the oxygen in the air would equal ……… part.

4. There is air till a height of about ……………km from the earth.

5. The layers of air nearer the earth bear …………. weight than the upper layers.

Answers.

1. There is air even in an empty container.

2. The air at a greater height from the earth is rare than the air nearer to the earth.

3. If all the air were divided into five parts, the oxygen in the air would equal one-fifth part.

4. There is air till a height of about 50 km from the earth.

5. The layers of air nearer the earth bear more weight than the upper layers.

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