The first law of thermodynamics is given by:

$1 \ cc$ of water at its boiling point $(100^{\circ} \ C)$ is converted into steam by supplying $540 \ \text{calories}$ of heat. The volume of steam is $1671 \ cc$. If atmospheric pressure is $1.013 \times 10^5 \ \text{Nm}^{-2}$ and $J = 4.18 \ \text{joule/cal}$, the approximate value of heat required to overcome the molecular attraction is ........ $\text{cal}$.

Write the sign convention for internal energy in thermodynamics.

Which of the following does not follow the first law of thermodynamics? $(W = \text{work}, Q = \text{heat}, \Delta U = \text{change in internal energy})$

$1\;g$ of water,of volume $1\;cm^{3}$ at $100^{\circ}C$,is converted into steam at the same temperature under normal atmospheric pressure $(=1 \times 10^{5}\;Pa)$. The volume of steam formed equals $1671\;cm^{3}$. If the specific latent heat of vaporisation of water is $2256\;J/g$,the change in internal energy is.....$J$.

When a system is taken from state $a$ to state $c$ along a path $abc$,it is found that $Q = 80 \ cal$ and $W = 35 \ cal$. Along path $adc$,$Q = 65 \ cal$. The work done $W$ along path $adc$ is: (in $cal$)