Gases best follow the facts given below
A) An ideal gas obeys the mathematical relation PV=nRT
B) Rates of diffusion of two gases are in the reciprocal ratio of square roots of their molecular weight
C) Total pressure of a mixture of non reacting gases is given by the algebric sum of their partial pressure
An ideal gas is captured in a glass tube of uniform arca of cross section by a  water column at a given temperature as shown

If the tube is held vertical, by what length the water column descends down?
(Density of mercury=13.6gm/cc) `(P_(atm)=76cm of Hg)`

Options

A. 2.2 cm
B. 3.2 cm
C. 1.03 cm
D. 4.07 cm

Answer

C

Explanation

Pressure due to water column in terms of mercury is given by `h_1d_1 = h_2d_2`
`27.2 xx 1 = h_2 xx 13.6 implies h_2 = 2 cm`
When held vertical , `P_("gas") = P_("atm") + 2 cm of Hg`
`= 76+ 2`
`= 78 cm of Hg`.
`P_1 V_1 = P_2V_2 = > 76 xx 40 xx A = 78 xx l xx A`
`implies l = 38.97 implies "descent" = 40 - 38.97`
`= 1.03 cm`.