Solid ammonium chloride dissociates according to $N{H}_{4}Cl(s)N{H}_3(g)+HCl(g).$ The dissociation vapour pressure of $N{H}_{4}Cl$ at $427C$ is $608$kPa but at $459C$ it has risen to $1115$kPa. Calculate $($i$)$ the equilibrium constant, $($ii$)$ the standard reaction Gibbs energy, $($iii$)$ the standard enthalpy, $($iv$)$ the standard entropy of dissociation, all at $427C.$ Assume that the vapour behaves as a perfect gas and that $r{H}_{}$ and $r{S}_{}$ are independent of temperature in the range given.