Question

Which of the following will function as buffer?
(1) $NaCl ^{\circ}+ NaOH$
(2) Borax $+$ Boric acid
(3) $NaH _{2} PO _{4}+ NaHPO _{4}$
(4) $NH _{4} Cl + NH _{4} OH$

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (C)

Buffer is a mixture of a weak acid/weak base and its conjugate base/conjugate acid. eg, borax
(conjugate base) $+$ boric acid (weak acid),
$NH _{4} Cl$ (conjugate acid) $+ NH _{4} OH$ (weak base).