What is the pH of a solution containing NH3 and NH4Cl?

[vaishakh]

0.05ml of NH3 is dissloved in a solution containing water followed by 0.27g of NH4Cl. If the Kb for NH4OH is 1.8 * 10^-5 find the pH value of the solution.
I am finding it difficult to predict the reactions that are going to happen here. I know to calculate Kh or the constant of hydrolysis of NH4Cl from here but how does NH3 dissolve in water. I think it mixes with H+ in the solution to form NH4+.
But I don't know how to continue.

 

[Borek]

This is classical buffer question.

Compare with this buffer question - not identical, but close.