Physics
Cloudy nights are warmer compared to clear cloudless nights, because clouds mainly

Produce heat and radiate it toward earth
Prevent cold waves from the sky descending on earth
Reflect back the heat given by earth
Absorb heat from the atmosphere send it towards earth

ANSWER DOWNLOAD EXAMIANS APP

Physics
A drop of liquid assumes spherical shape because:

A sphere has the least surface area for a given volume
Inter molecular forces are weak in liquids
Intermolecular forces are strong in liquids
A sphere has the largest surface area for a given volume

ANSWER DOWNLOAD EXAMIANS APP