The volume (\( V \)) of a monatomic gas varies with its temperature (\( T \)) as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state \( A \) to state \( B \), is

From the graph, \( V \propto T \), which represents an isobaric process (\( P = \text{constant} \)). For an isobaric process, work done \( W = P \Delta V = nR \Delta T \) and heat absorbed \( Q = n C_p \Delta T \). For a monatomic gas, \( C_p = \frac{5}{2}R \). Thus, the ratio \( \frac{W}{Q} = \frac{nR \Delta T}{\frac{5}{2}nR \Delta T} = \frac{2}{5} \).