Question

Select the correct statements.
(I) Increase in relative humidity decreases the density of air
(II) Increase in relative humidity decreases the rate of evaporation of water
(III) Increase in relative humidity decreases the velocity of sound
(IV) Increase in relative humidity increases the velocity of sound

• A. I, II, IV
• B. I, II, III
• C. I, II
• D. I, IV

Answer 1

The correct option is A I, II, IV

humidity, a moisture content of the atmosphere, a primary element of climate. Humidity measurements include absolute humidity, the mass of water vapour per unit volume of natural air; relative humidity (usually meant when the term humidity alone is used), the ratio of the actual water-vapour content of the air to its total capacity at the given temperature; Humidity is measured by means of a hygrometer. The rate of evaporation decreases as the moisture content of the air increases and approaches saturation.
An increase in the amount of humidity in the air increases the speed only small amount. Since humidity can vary so much, and since the amount of change of speed with an extreme change in humidity is less the 0.5%, the speed of sound in air is usually simply measured in dry air, neglecting the effect of humidity.
The amount of water vapour in air influences density. Water vapour is a relatively light gas compared to diatomic Oxygen and diatomic Nitrogen - the dominant components in air.
When water vapour content increases in the moist air the amount of Oxygen and Nitrogen decreases per unit volume and the density decreases because the mass is decreasing.