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

Match the following according to conversion by heat:

Column-$I$	Column-$II$
$(a)$ Required heat to convert solid into gaseous.	$(i)$ Latent heat of fusion
$(b)$ Required heat to convert solid into liquid.	$(ii)$ Latent heat of vaporization

Explain the three states of matter and the process of change in states.

Explain the process of melting of ice with an explanation of freezing,melting,and melting point.

Boiling water is changing into steam. The specific heat of boiling water is

Two substances $A$ and $B$ of equal mass $m$ are heated at a uniform rate of $6 \, cal \, s^{-1}$ under similar conditions. $A$ graph between temperature and time is shown in the figure. The ratio of heat absorbed $H_A/H_B$ by them for complete fusion is