Question

deserts are very hot during day and cold at night give reason

Answer 1

Deserts are very hot during the day and cold during night because of the sands as sands heats fastly and cools fastly.

Answer 2

deserts are hot during day and cold during night because of the lack of water deserts cannot support much vegetation........So during night time the sun is not shinning the sand loses all his heat making the night cool 
Sand is the biggest reason for this .