In the given (V $$-$$ T) diagram, what is the relation between pressure P₁ and P₂?

The amount of heat energy required to raise the temperature of 1 g of Helium at NTP, from T₁K to T₂K is

An ideal gas goes from state A to state B via three different processes as indicated in the P-V diagram.



If Q₁, Q₂, Q₃ indicate the heat absorbed by the gas along the three processes and $$\Delta $$U₁, $$\Delta $$U₂, $$\Delta $$U₃ indicate the change in internal energy along the three processes respectively, then

One mole of an ideal gas goes from an initial state A to final state B via two processes : It first undergoes isothermal expansion from volume V to 3V and then its volume is reduced from 3V to V at constant pressure. The correct P-V diagram representing the two process is