Calculate the amount of $(NH_4)_2SO_4$ in grams which must be added to $500 \ mL$ of $0.200 \ M \ NH_3$ to yield a solution with $pH = 9.35$ ($K_b$ for $NH_3 = 1.78 \times 10^{-5}$).

Buffer Solution	Volume of $0.1 \ M$ Weak Acid (mL)	Volume of $0.1 \ M$ Sodium Salt (mL)
$I$	$4.0$	$4.0$
$II$	$4.0$	$40.0$
$III$	$40.0$	$4.0$
$IV$	$0.1$	$10.0$

Which of the two sets of buffer solutions have the least $pH$?

$A$ buffer solution contains $0.1 \ mol$ of sodium acetate dissolved in $1000 \ cm^{3}$ of $0.1 \ M$ acetic acid. To the above buffer solution,$0.1 \ mol$ of sodium acetate is further added and dissolved. The $pH$ of the resulting buffer is

For a $10 \, mL$ solution containing $0.1 \, M \, NH_4Cl$ and $0.01 \, M \, NH_4OH$,which of the following additions will not change the $pH$ of the solution?

Which of the following is a buffer solution?

$50 \, mL$ of $2 \, N$ acetic acid mixed with $10 \, mL$ of $1 \, N$ sodium acetate solution will have an approximate $pH$ of $(K_a = 10^{-5})$