Question

In a mercury thermometer, the ice point (lower fixed point) is marked as ${10}^0$ and the steam point (upper fixed point) is marked as ${130}^0$. At ${40}^{0}C$ temperature, what will this thermometer read?

• A. ${78}^0$
• B. ${66}^0$
• C. ${62}^0$
• D. ${58}^0$

Answer 1

Answer: (D)

${58}^0$

Let the temperature in given scale be $x$.

Consider a straight line as a relation between given and celsius scale.

We get, $\frac{x-10}{130-10}=\frac{40-0}{100-0}$

where, 0 and 10 are lowest fixed point for celsius and given scale and 130 and 100 are highest fixed point for given and celsius scale.

$\Rightarrow \frac{x-10}{130-10}=\frac{40}{100}$

$\Rightarrow 100x-1000=4800$

$\Rightarrow 100x=5800$

$\Rightarrow x={58}^0$