`C_(2)H_(6)(g) hArr C_(2)H_(4)(g)+H_(2)(g)`

`{:("Initial Pressure",4.0 atm,,0,0),(At eq,4-p,,p,p):}`

`K_(p)=(p_(C_(2)H_(2))xxp_(H_(2)))/p_(C_(2)H_(6))`

`:. 0.04=p^(2)/(4-p)`

or `p^(2)=0.16-0.04p`

or `p^(2)+0.04p-0.16=0`

`:. P=(-0.04+-sqrt(0.0016-4(-0.16)))/(2)=(-0.04+-0.89)/(2)`

Taking positive value,

`p=0.80/2=0.40`

`:. [C_(2)H_(6)]_(eq)=4-0.40 atm =3.60 atm`