Question

There are two identical vessels filled with equal amounts of ice. The vessels are of different metals. If the ice melts in the two vessels in 20 and 35 minutes respectively, the ratio of the coefficients of thermal conductivity of the two metals is:  

Options

• 4 : 7

• 7 : 4

• 16 : 49

• 49 : 16

Answer 1

7 : 4

Explanation:

${\displaystyle \text{K}\propto \frac{1}{\text{t}}}$

∴ ${\displaystyle \frac{{\text{K}}_1}{{\text{K}}_2}=\frac{{\text{t}}_2}{{\text{t}}_1}}$

= ${\displaystyle \frac{35}{20}}$

= ${\displaystyle \frac{7}{4}}$

= 7 : 4