Ametal wire is clamped between two vertical walls.At $20 ^o C$ the unstrained length of the wire is exactly equal to the separation between walls. If the temperature of the wire is decreased the graph between elastic energy density $(u)$ and temperature $(T)$ of the wire is

The portion $AB$ of the indicator diagram representing the state of matter denotes

A closed bottle containing water at $30°C$ is carried to the moon in a space-ship. If it is placed on the surface of the moon, what will happen to the water as soon as the lid is opened

Liquid oxygen at $50\  K$ is heated to $300\  K$ at constant pressure of $1\  atm$. The rate of heating is constant which of the following graphs represents the variation of temperature with time

Explain three states and change in states for matter.

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