Question

A tube of length 50 cm is containing a gas in two sections separated by a mercury coloumn of length 10 cm as shown in figure. The open end of tube is just inside the Hg surface in container find pressure of gas in two sections. [Assume atmospheric pressure = 75 cm of Hg column]

• A. Pressure in the lower half of gas = P${}_0$ = 75 cm of Hg column
  Pressure of gas in upper half m of the column - (75 - 10) = 65 cm of Hg
• B. Pressure in lower half of gas = P${}_0$ = 85 cm of Hg column
  Pressure of gas in upper half m of the column - (85 - 10) = 75 cm of Hg
• C. Pressure in the lower half of gas = P${}_0$ = 65 cm of Hg column
  Pressure of gas in upper half m of the column - (65 - 10) = 55 cm of Hg
• D. Pressure in the lower half of gas = P${}_0$ = 95 cm of Hg column
  Pressure of gas in upper half m of the column - (95 - 10) = 85 cm of Hg

Answer 1

The correct option is A Pressure in the lower half of gas = P${}_0$ = 75 cm of Hg column

Pressure of gas in upper half m of the column - (75 - 10) = 65 cm of Hg
$pressure=h\times d\times g$

here density and g are constant.

As in the lower section height of mercury is not raised Pressure in lower section $=P_{a}tm=75cmofHg$

As in the upper section height of mercury raised by 10cm $Pressure=75-10=65cmofHg$