Physical Science, module 2

Question 1

Define “absolute humidity”.

Answer 1

The mass of water vapour contained in a certain volume of air.

Question 2

Define “relative humidity”.

Answer 2

A quantity expressing humidity as a percentage of the maximum absolute humidity for that particular temperature.

Question 3

Define “greenhouse effect”.

Answer 3

The process by which certain gases (principally water vapour, methane, and ozone) trap heat that would otherwise escape the earth’s atmosphere and radiate into space.

Question 4

Define “parts per million”.

Answer 4

The number of molecules (or atoms) of a substance in a mixture for every million molecules (or atoms) in that mixture.

Question 5

Why does sweating cool people down?

Answer 5

Because the process of evaporation uses up energy, cooling the surface that the water is on.

Question 6

What is the percentage of nitrogen in dry air?

Answer 6

78%.

Question 7

What is the percentage of oxygen in dry air?

Answer 7

21%.

Question 8

How many ppm are equivalent to 1%?

Answer 8

1% = 10,000 ppm

Question 9

What does a scrubber do in a smokestack?

Answer 9

It absorbs sulphur oxides produced by coal burning.

Question 10

Define “humidity”.

Answer 10

The moisture content of the air.