Calculate the amount of Ca`(OH)_(2)` required to be dissolved to prepare 250 mL aqueous solution of pH=12.

How many moles of Ca(OH)_(2) must be dissolved to produce 250 mL of an aqueous solution of pH 10.65 , assuming completer dissociation ?

Calculate the mass of Na_(2)CO_(3) required to prepare 250 ml of 0.5 N solution.

Calculate the amount of oxalic acid (eq. wt. 63) required to prepare 500 ml of its 0.10N solution.

Calculate the amount of benzoic acid (C_(6)H_(5)COOH) required for preparing 250 ml of 0.15 M solution in methanol.