Question

A thermometer has 20 equal divisions between ${90}^{\circ }C$ and ${100}^{\circ }C$ marks. A student
while determining the boiling point of water finds that the mercury thread becomes
stationary at the ${19}^{th}$ mark above ${90}^{\circ }C$. He should record the boiling point of water
as :

• A. ${90.19}^{\circ }C$
• B. ${99.5}^{\circ }C$
• C. ${109}^{\circ }C$
• D. ${119}^{\circ }C$

Answer 1

Answer: (B)

${99.5}^{\circ }C$

Thermometer is the device that is used to measure the temperature of any substance. Here the level of mercury is checked as mercury is expanded at high temperature.

There are $20$ divisions between ${90}^{0}c$ and ${100}^{0}C$. Each division will be calibrated as $\frac{10}{20}={0.5}^{0}C$.

So, the ${19}^{th}$ mark indicates,

$90+(0.5\times 19)={99.5}^{0}C$