Lemon juice normally has a $pH$ of $2$. If all the acid the lemon juice is citric acid and there are no citrate salts present, then what will be the citric acid concentration $\left[Hcit\right]$ in the lemon juice? (Assume that only the first hydrogen of citric acid is important)
$HCit\iff H^{+}+Ci{t}^{-}$, $K_a=8.4\times {10}^{-4}mol{L}^{-1}$

Lemon juice has a pH = 2.1 . If all the acid in lemon is citric acid $(H\text{Cit.}\iff H^{+}+{\text{Cit}}^{-1})$ and $K_a$ for citric acid is $8.4\times {10}^{-4}$ mole/litre, what is the concentration of citric acid in lemon juice ?

How many times of the acetic acid concentration, acetate salt should be added to a given acetic acid solution to obtain a solution of pH = 7.0 ($K_a$ for $C{H}_{3}COOH=1.8\times {10}^{-5}$ ) .

The acid dissociation constant of uric acid is $K_a=4.0\times {10}^{-6}$ M. The pH of a sample of urine is 6.0. What is the ratio of concentration of urate ion to uric acid in the urine?

At what molar concentration, the pH of nitrous acid should be 2.0 ? $(K_a=4.5\times {10}^{-4})$

Calculate the concentration of the formate ion present in $0.100$ M formic acid $\left(HCOOH\right)$ solution at equilibrium $(K_a=1.7\times {10}^{-4})$.

What is the $pH$ of the solution when $0.20mol$ of $HCI$ is added to $1L$ of a solution containing
a. $1M$ each of acetic acid and acetate ion.
b. $0.1M$each of aceta acid and acetate ion.
Assume the total volume is $1L.K_a$ for acetic acid is $1.8\times {10}^{-5}$.

What is the pH of the solution when 0.2 mole of hydrochloric acid is added to one litre of a solution containing 1 M acetic acid and acetate ion ? Assume that the total volume is one litre .$K_a$ for $C{H}_{3}COOH=1.8\times {10}^{-5}$.

The $pH$ of milk, black coffee, tomato juice, lemon juice and egg white are $6.8,5.0,4.2,2.2$ and $7.8$ respectively. Calculate corresponding hydrogen ion concentration in each.

$K_a$ for acid HA and HB are $2.1\times {10}^{-4}$ and $1.1\times {10}^{-5}$ respectively. The relative strength of acid if concentration is same:-

What concentration of acetic acid is needed to give a hudrogen ion concentration of $3.5\times {10}^{-4}M$?
$(K_a=1.8\times {10}^{-5})$?