Why is cooking faster in a pressure cooker?

Find the amount of heat supplied to decrease the volume of an ice-water mixture by $1 \, cm^3$ without any change in temperature. (Given: $\rho_{ice} = 0.9 \rho_{water}$,$L_{ice} = 80 \, cal/g$).

$A$ cylinder of mass $1\,kg$ is given heat of $20000\,J$ at atmospheric pressure. If the initial temperature of the cylinder is $20\,^oC$,then the work done by the cylinder will be .......$J$. (Given: Specific heat of cylinder $= 400\,J\,kg^{-1}\,^oC^{-1}$,Coefficient of volume expansion $= 9 \times 10^{-5}\,^oC^{-1}$,Atmospheric pressure $= 10^5\,N/m^2$,and density of cylinder $= 9000\,kg/m^3$)

$A$ closed bottle containing water at $30^{\circ}C$ is carried to the moon in a spaceship. If it is placed on the surface of the moon,what will happen to the water as soon as the lid is opened?

What type of changes occur in an object by heating it?

$A$ hailstone of mass $42 \,g$ falls from a height of $1.8 \,km$. If its entire potential energy is converted into latent heat, what is the mass of the hailstone remaining when it reaches the ground (in $\,g$)? $\left(g=10 \,ms^{-2}, L_{\text{ice}}=3.36 \times 10^5 \,J \,kg^{-1}\right)$