Question

The reading of a centigrade thermometer coincides with that of Fahrenheit thermometer for a liquid. The temperature of the liquid $\left(\text{in}{C}^{\circ }\right)$ is

• A. $-{40}^{\circ }\text{C}$
• B. $0^{\circ }\text{C}$
• C. ${100}^{\circ }\text{C}$
• D. ${300}^{\circ }\text{C}$

Answer 1

The correct option is A $-{40}^{\circ }\text{C}$

Relation between centigrade and fahrenheit readings is,
$\frac{C}{5}=\frac{F-32}{9}...\left(i\right)$
Since centigrade and fahrenheit thermometer readings are equal, i.e $C=F$
$\Rightarrow$Putting in Eq $\left(i\right)$,
$\frac{C}{5}=\frac{C-32}{9}$
$4C=-160$
$\therefore C=-{40}^{\circ }$