[PH_(3)" is purified by the "],[" addition of "]

Benzen is purified by

Assertion (A): The pH of an aqueous solution of CH_(3)COOH remains unchanged on the addition of CH_(3)COONa . Reason (R) : The pH of an aqueous solution of CH_(3)COOH remains unchanged on the addition of CH_(3)COONa . Reason (R) : The ionisation of CH_(3)COOH is supressed by the addition of CH_(3)COONa .

Mercury is purified by :

Oils are purified by: