A particle covers equal distance in equal intervals of time. It is said to be? 1.at rest
2.moving with constant acceleration
3.moving with constant velocity
4.moving with constant speed

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d

d. air pressure decreases as altitude increases.