Identify the pair of intensive properties from the following.

Which of the following processes involves zero work done?

Which statement is correct?

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 ........ .

For one mole of an ideal gas,which of these statements must be true?
$(a)$ $U$ and $H$ each depend only on temperature.
$(b)$ Compressibility factor $Z$ is not equal to $1$.
$(c)$ $C_{P,m} - C_{V,m} = R$
$(d)$ $dU = C_V dT$ for any process.

It is a general principle that the less energy a system contains,it is: