A solution is prepared by mixing 10 mL of 1.0 M acetic acid and 20 mL of 0.5 M sodium acetate and diluted to 100 mL . If the $\mathrm{p} K_a$ of acetic acid is 4.76, then the pH of the solution is

Ammonia is a Lewis base because it is

How many of the following are diprotic acids? Citric acid, chromic acid, oxalic acid, pyrosulphuric acid, sulphurous acid

$$ \text { Match the following } $$

$$ \text { Metal sulphide } $$		$$ \text { Solubility product } $$
(A)	$$ \mathrm{PbS} $$	(I)	$$ 4.0 \times 10^{-53} $$
(B)	$$ \mathrm{HgS} $$	(II)	$$ 8.0 \times 10^{-28} $$
(C)	$$ \mathrm{MnS} $$	(III)	$$ 1.6 \times 10^{-24} $$
(D)	$$ \mathrm{ZnS} $$	(IV)	$$ 2.5 \times 10^{-13} $$

$$ \text { The correct match is } $$