Answer:
a) decrease
b) increase
c) decrease
Step-by-step explanation:
a) The density of water decreases as water changes from liquid to steam.
The density of substances are higher when their molecules are very close to each other having strongest bonding forces. When water is change from liquid to steam it means water molecules are not close to each other as they are in liquid state because now water is changed into gaseous form and molecules are further apart from each other. Thus, density goes to decrease.
b) As the temperature increases, the rate of diffusion of a gas increase.
As temperature increases molecules gets more kinetic energy and rate of diffusion increases.
c) At constant volume, if the temperature of a gas is decreases, its pressure decreases.
According to Gay-Lussac Law,
The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.
Mathematical relationship:
P₁/T₁ = P₂/T₂
As temperature decreases its pressure also goes to decrease and vice versa.