Two moles of an ideal gas expand spontaneously into a vacuum. The work done is ............. $Joule$.

Two moles of an ideal gas are expanded isothermally from $15 \ dm^3$ to $20 \ dm^3$. If the amount of work done is $-6 \ dm^3 \ bar$,find the external pressure needed to obtain this work.

Which one of the following is an extensive property?

Conditions of standard state used in thermochemistry is

For the process $CO_{2(s)} \rightarrow CO_{2(g)}$,which of the following is true?

Fill in the blanks:
$(i)$ The change in heat energy during a chemical reaction at constant volume is called .......
$(ii)$ During a ....... process,there is no absorption or evolution of heat.
$(iii)$ The equation $\Delta G = \Delta H - T \Delta S$ was proposed by .......