A open ended mercury manometer is used to measure the pressure exerted by a trapped gas as shown in the figure. Initially manometer shows no difference in mercury level in both columns as shown in diagram.
After sparking 'A' dissociates according to following reaction
`2A(g)rarr 3B(g)+2C(g)`
If pressure of Gas "A" dissociates to 0.8 atm, then (Assume temperature to be constant and is 300 K)

Options

A. 9 cm Hg
B. 18 cm Hg
C. 27 cm Hg
D. None of these

Answer

a

Explanation

(a) `{:((a),2NH_(3)(g),to,N_(2)(g), +, 3H_(2)(g)),("Before sparking"," "76 ,, " " 0,, 0),("After sparking", 76-2x,," "x,,3x),("at eqm",,,,,):}`
Increase in pressure `2x=6, x=3cm Hg`
Partial pressure of `H_(2)=3xx3=9cmHg`