4 mole of NH₄OH and 1 mole of H₂SO₄ are mixed and diluted to 1 lit solution. The pK_b of NH₄OH is 4.8 . The pH of solution is

Following reaction will occur

	2NH4OH	+	H2SO4	(NH4)2SO4 + 2H2O
t = 0	4 mol		1 mol	0             0
	(4 - 2) mol		(1 - 1)  mol	1 mol      2 mol
	= 2 mol		0 mol

NH₄OH is monovalent whereas (NH₄)₂SO₄ is bivalent;

P^OH = P^K_b + $\log \frac{1\times 2}{2};$

P^OH = 4.8 

P^H = 14 - 4.8 = 9.2