1 mole of an ideal gas expands isothermally and reversibly by decreasing pressure form $$210 \mathrm{~kPa}$$ to $$105 \mathrm{~kPa}$$ at $$300 \mathrm{~K}$$. What is the work done? $$\left(\mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)$$

When 1 mole of gas is heated at constant volume, the temperature rises form $$273 \mathrm{~K}$$ to $$546 \mathrm{~K}$$. If heat supplied to the gas is $$\mathrm{x~J}$$, then find the correct statement from following.

What is the value of $$\mathrm{\Delta H-\Delta U}$$ for the formation of 2 moles of ammonia from $$\mathrm{H_{2(g)}}$$ and $$\mathrm{N_{2(g)}}$$ ?

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