Solution :
Millimoles of hydrocyanic acid = 225 x 0.368
= 82.8
Millimoles of potassium cyanide = 225 x 0.360
= 81
Millimoles of sodium hydroxide = 51.3
Therefore,
pOH = pKb + log [salt - C / bas + C]
= 4.74 + log[82.8 - 51.3 / 81 + 51.3]
= 4.102
Therefore, pH = 9.05