If a gas expands at constant temperature and pressure,then its:

Fill in the blanks:
$(i)$ The conversion of graphite into diamond is a ........ process.
$(ii)$ $1 \text{ calorie} = ........ \text{ Joules}$.
$(iii)$ Work done by the system can be calculated by the equation ........ .
$(iv)$ The change in heat energy during a chemical reaction at constant volume is called ........ .

Point out the wrong statement in relation to enthalpy.

Expansion of a gas in vacuum is called free expansion. Calculate the work done and the change in internal energy when $1 \ L$ of ideal gas expands isothermally into vacuum until its total volume is $5 \ L$?

For which of the following reactions is $\Delta U = \Delta H$?

The internal energy of an ideal gas increases during an isothermal process when the gas is