Physics
It is easier for a man to swim in sea water, than in river water because

The density of sea water is more than the density of river water
The sea is-deeper than the river
The sea is wider than the river
The density of sea water is lesser than the density of river water

ANSWER DOWNLOAD EXAMIANS APP

Physics
Lightning is produced when

Similar charges of electricity rush towards each other and then get repelled
Strong opposite charges in different clouds break down the resistance offered by the intervening air
Clouds strike against impurities in air and the friction burns up these impurities
Water vapour produces electricity in the clouds

ANSWER DOWNLOAD EXAMIANS APP