Question

Find neon pressure in manometer , when atmospheric pressure is 650 torr.

• A. 665 torr
• B. 80 torr
• C. 570 torr
• D. 650 torr

Answer 1

The correct option is C 570 torr

Given : $P_B=650$ mm Hg

Difference in height of Hg column $h=47-39=8$ cm $=80$ mm

$\therefore$ Pressure in Hg column $P_{column}=80$ mm Hg

From figure, $P_A=P_B$ where $P_A=P_{Ne}+P_{column}$

$\therefore$ $P_{Ne}+80=650$ $⟹P_{Ne}=570$ mm Hg or $570$ torr