Question

The state of a mole of an ideal gas changed from state $A$ at pressure $2P$ and volume $V$ follows four different processes and finally returns to initial state $A$ reversibly as shown in the graph, answer the following question.

Which is the kind of process followed from state $A$ to state $B$?

• A. Expansion from state $A$ to state $B$ occurs at constant pressure (isochoric expansion) $=2P$
  
• B. None of these
• C. Expansion from state $A$ to state $B$ occurs at constant pressure (isobaric expansion) $=3P$
  
• D. Expansion from state $A$ to state $B$ occurs at constant pressure (isobaric expansion) $=2P$
  

Answer 1

Answer: (D)

From the curve, it can be easily observed that during expansion from state $A$ to state $B$ the pressure is constant at $2P$. And since a process in which pressure remains constant is known as an isobaric process, the process thus being followed is isobaric expansion at a constant pressure of $2P$.

As volume is increased from V to 2V so expansion takes place.