247) M(OH)_x has K_sp = 4 x 10⁻¹² and solubility 10⁻⁴. x is:

248) To a mixture of NH₄Cl and NH₃ in water, a further amount of NH₄Cl is added. The pH of the mixture is:

249) What will be the pH of an aqueous solution of 1M ammonium formate assuming complete dissociation? (pK_a for formic acid = 3.8 and pK_b for ammonia = 4.8)

250) pH of 0.02M solution of pyridinium hydrochloride (a salt of strong acid and weak base) is 3.44. The ionisation constant of pyridine is:

251) 40 mL of 0.1M ammonia solution is mixed with 20 mL of 0.1M HCl. What is the pH of the mixture? (pK_b of ammonium solution is 4.74)