A good refrigerant should have

high latent heat of vaporisation and low freezing point
high operating pressures and low freezing point
high specific volume and high latent heat of vaporisation
low C.O.P. and low fre
✅ The correct answer is option A.

When a body is placed over a liquid, it will sink down if

gravitational force is equal to the upthrust of the liquid
gravitational force is less than the upthrust of the liquid
gravitational force is more than the upthrust of the liquid
none of the above
✅ The correct answer is option C.