Why does temperature decrease with higher altitude?
air is held strongly together by gravity, so there is less heat transfer.
air density is lower, so there is less heat transfer.
air density is higher, so there is less heat transfer.
air pressure is higher, so there is less heat transfer.

Option (b) is the correct answer.

Explanation:

Radiation is absorbed by the ground of Earth and this heats the surroundings along with tropospheric air through conduction and convection process.

But as we go at higher altitude then gases present in the troposphere absorb very less amount of incoming solar radiations.

As a result, air molecules move farther away from each other and there will be decrease in density of air due to less heat transfer.

Thus, we can conclude that temperature decrease with higher altitude as air density is lower, so there is less heat transfer.  

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.