## Physics What is the principle of a ''Life Jacket"?

The person can sit on it like a raft
It provides oxygen to a drowning person
It decreases the volume of the person to keep him afloat
It increases the volume of the person to keep him afloat

Volume
Specific gravity
Density
Mass

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

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

## Physics A piece of wood is held under water. The upthrust on it will be:

Less than weight of the wood
More than weight of the wood
Equal to the weight of the wood
Zero

## Physics An egg sinks in soft water but floats in a concentrated solution of salt because

The density of salt solution exceeds the density of eggs
Water has high surface tension
Albumin dissolves in salt solution and egg becomes lighter
Egg absorbs salt from the solution and expands