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

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 ........ $cal/g$.

$A$ 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:

The figure given below shows the cooling curve of a pure wax material after heating. It cools from $A$ to $B$ and solidifies along $BD$. If $L$ and $C$ are the respective values of latent heat and the specific heat of the liquid wax,the ratio $L/C$ is

$A$ solid substance is at $30^{\circ}C$. To this substance,heat energy is supplied at a constant rate. The temperature versus time graph is as shown in the figure. The substance is in the liquid state for the portion of the graph:

The latent heat of vaporization of a substance is always