JEE Main 2015 · 10 Apr · Shift 1 · Physics Q10

PhysicsSingle correct+4 / -1Question 10 of 90

An ideal gas goes through a reversible cycle a→b→c→d has the V - T diagram shown below. Process d→a and b→c are adiabatic.

The corresponding P - V diagram for the process is (all figures are schematic and not drawn to scale) :

a→b at high constant pressure (expansion), b→c adiabatic down, c→d at low constant pressure (compression), d→a adiabatic up

d→c at high constant pressure, a→b at low constant pressure

a→b at high constant pressure with d→c at low pressure, curves bulging the other way

d→c at high constant pressure, a→b at low constant pressure, curves bulging the other way

Answer and worked solution

Official answer: A

In the V-T diagram, a→b and c→d are straight lines towards the origin: isobaric, with $V\propto T$ .

a→b has the smaller slope $\frac VT$ , so the higher pressure. It goes from a to b with V increasing.
c→d is at low pressure with V decreasing.
b→c and d→a are adiabats.

So a and b lie on the upper line (b to the right), and d and c on the lower one: graph (1).

JEE Main 2015 · 10 Apr · Shift 1, Physics question 10