An amount of solid ` NH_4 HS ` is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm pressure . Ammonium hydrogen sulphide decomposses to yield `NH_3 and H_2S ` gases in the flask. When the decomposition reaction reaches equilibrium , the total pressure in the flask rises to 0.84 atm. The equilibrium constant for `NH_4HS ` decomposition at this temperature is

Options

A. `0.11`
B. `0.17`
C. `0.18`
D. `0.30`

Answer

A

Explanation

`NH_(4)HS(s)hArrNH_(3)(g)+H_(2)S(g)`
`{:("Initial presens",0,0.5,0),("At equi.",0,0.5+x,x):}`
Total pressure`=0.5+2x=0.84 therefore x=0.17` atm
`K_(P)=P_(NH_(3))xxP_(H_(2)S=0.11 atm^(2)`.