What is the process of changing the state of matter called?

Latent heat of vaporisation of water is $22.6 \times 10^5 \ J \ kg^{-1}$. The amount of heat needed to convert $100 \ kg$ of water into vapour at $100^{\circ} C$ is

$A$ metallic ball and a highly stretched spring are made of the same material and have the same mass. They are heated so that they melt. The latent heat required:

$A$ solid material is supplied with heat at a constant rate and the temperature of the material changes as shown in the graph. From the graph,the false conclusion drawn is:

At $100^{\circ}C,$ the substance that causes the most severe burn is:

An experiment takes $10\, minutes$ to raise the temperature of water in a container from $0\,^oC$ to $100\,^oC$ and another $55\, minutes$ to convert it totally into steam by a heater supplying heat at a uniform rate. Neglecting the specific heat of the container and taking the specific heat of water to be $1\, cal/g\,^oC$,the heat of vaporization according to this experiment will be ........ $cal/g$.