Question

( 1 mathrm{atm}=760 mathrm{mmHg} )
( 760 mathrm{mmHg}=mathrm{mm} ) glycerine ( left(frac{text { density of glycerine }}{text { density of } mathrm{Hg}}right) )
( 760 mathrm{mmHg}=mathrm{mm} ) glycerine ( left(frac{2.72}{13.6}right) )
or, ( mathrm{mm} ) glycerine ( , mathrm{P}_{0}=3800 mathrm{mmHg} )
( mathrm{P}_{mathrm{gas}}=mathrm{P}_{0}-mathrm{h} )
[
begin{aligned}
=& 3800 mathrm{mm}-2.5 times 10^{3} mathrm{mm}
=& 3800-2500
=& 1300 mathrm{mm}
text { or }, mathrm{P}_{text {gas }}=frac{1300}{3800}=0.34 mathrm{atm}
end{aligned}
]
Now
( mathrm{PV}=mathrm{nRT} )
or, ( mathrm{n}=frac{mathrm{PV}}{mathrm{RT}} )
or, ( mathrm{n}=frac{0.34 times 10}{0.0821 times 300}=0.138 mathrm{mol} )
Hence, correct answer is ( (mathrm{B}) )

# 8. Air (1 atm.) 101 A gas is filled in the glass bulb of capacity 10 litre as shown in figure at 300 K Density of glycerine = 2.72 g/ml. Density of mercury = 13.6 g/ml. Now, select the correct statement(s) among the following: (A) pressure of the gas is 3.28 atm (B) pressure of the gas is 0.342 atm (C) moles of the gas in the bulb are 0.34 (D) moles of the gas in the bulb are 1.33 Glicerine-

Solution