Is $P\Delta V$ an extensive or intensive variable?

Write and explain the first law of thermodynamics.

If $Q$,$E$,and $W$ denote respectively the heat added,change in internal energy,and the work done by a closed cycle process,then

$1\,kg$ of water at $100^{\circ}C$ is converted into steam at $100^{\circ}C$ by boiling at atmospheric pressure. The volume of water changes from $1.00 \times 10^{-3}\,m^3$ as a liquid to $1.671\,m^3$ as steam. The change in internal energy of the system during the process will be $........kJ$ (Given latent heat of vaporisation $= 2257\,kJ/kg$. Atmospheric pressure $= 1 \times 10^5\,Pa$)

If the heat given to a system is $35 \ J$ and the work done on the system is $15 \ J$,then the change in the internal energy of the system is ... $J$?

The first law of thermodynamics is concerned with the conservation of