Question

Two substances A and B of equal mass m are heated at uniform rate of 6 cal s^–1 under similar conditions. A graph between temperature and time is shown in figure. Ratio of heat absorbed H_A / B_B by them for complete fusion is-

• A. $\frac{9}{4}$
• B. $\frac{4}{9}$
• C. $\frac{8}{5}$
• D. $\frac{5}{8}$

Answer 1

Answer: (C)

$\frac{8}{5}$

Answer 2

From given curve,

Melting point for A = 60⁰C and melting point for B = 20⁰

Time taken by A for fusion = (6 – 2) = 4 minute

Time taken by B for fusion = (6.5 – 4) = 2.5 minute

Then $\frac{H_{A}}{H_{B}}$=$\frac{6 \times 4 \times 60}{6 \times 2.5 \times 60}$=$\frac{8}{5}$