Question

A thermometer has 20 equal divisions between 90˚C and 100˚C marks. A student while determining the boiling
point of water finds that the mercury thread becomes stationary at the 19th mark above 90˚C. He should record the
boiling point of water as :
(a) 90.19˚C (b ) 99.5˚C (c) 109˚C (d) 119˚C

Answer 1

(B) 99.5°C
Since there are 20 equal marks between 90°C & 100°C, therefore temperature at 1st mark
=(100°C-90°C )×1/20 +90°C
=90.5°C
Therefore temperature at 19th mark
=10°C×19/20 +90°C
=99.5°C

Answer 2

A student should record the boiling point of water as (b) 99.5˚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.

Since, there are 20 equal division between 90˚C and 100˚C marks hence each division stands for 0.5˚C.

The mercury level raised till 19th mark means it reached to 9.5˚C. Hence the recorded boiling point of water must be

$90+9.5 = 99.5\quad Degree\quad Celsius$