Write the equilibrium constant expression k for the

Question

Write the equilibrium constant expression, K, for the following reaction: 

If either the numerator or denominator is 1, please enter 1

Pb²⁺(aq) + S^2-(aq) <----->  PbS(s) 

K = ( / )

Write the equilibrium constant expression, K, for the following reaction: 

If either the numerator or denominator is 1, please enter 1

NH₄Cl(s) <-----> NH₃(g) +  HCl(g) 

K =  ( / )