Question

Which of the substances $A, B$ and $C$ has the lowest heat capacity? If heat is supplied to all of them at equal rates, the temperature versus time graph is shown below.

• A. $A$
• B. $B$
• C. $C$
• D. All have equal specific heat

Answer 1

Answer: (C)

Substances having more heat capacity take longer time to get heated to a higher temperature and longer time to get cooled.

If we draw a line parallel to the time axis, then it cuts the given graphs at three different points, i.e. $A, B$ and $C$.
Corresponding points on the time axis show that
Heat capacity, $S=\frac{t_{C} >t}{\Delta t}$
As $\Delta Q$ is same, so $S \propto \frac{1}{\Delta t}$
So, from relation (i) and (ii), we can say that
$\therefore S_{C}< S_{B}< S_{A}$
Hence, substance $C$ has lowest heat capacity.