Question

Which has the highest $pH$?
A.$C{H_3}COOK$
B.$N{a_2}C{O_3}$
C.$N{H_4}Cl$
D.$NaN{O_3}$

Answer 1

$pH$ is defined as the potential of a substance in water or aqueous solution to show acidity or basicity. It is usually a scale ranging from $0$ to $14$. Water is a neutral solution and its $pH$ is $7$. Acids show pH range $0$ to $7$ and bases show $pH$ range $7$ to $14$.

Complete step by step answer:
All the given compounds are salts by nature and will dissociate in water. is measured as the inverse of hydrogen ion concentration. The lower the hydrogen ion concentration the higher will be the and vice versa.
Let us consider each salt one by one.
$C{H_3}COOK$ salt is generated from weak acid $C{H_3}COOH$ and strong base $KOH$. So the aqueous solution of $C{H_3}COOK$ will consists of one mole of $C{H_3}COOH$ and one mole of $KOH$ and will be basic in nature and the $pH$ will be greater than $7$.
$N{a_2}C{O_3}$ salt is basic in nature. As the aqueous solution of $N{a_2}C{O_3}$ will consists of two moles of $NaOH$ and one mole of ${H_2}C{O_3}$ and so will be basic in nature and the $pH$ will be greater than $10$.
$N{H_4}Cl$ salt is made by combining strong acid $HCl$ and a weak base $N{H_{4}}OH$. So the aqueous solution of $N{H_4}Cl$ will consists of one mole of $N{H_{4}}OH$ and one mole of $HCl$ and will be acidic in nature and its $pH$ will be less than $7$.

$NaN{O_3}$​ salt is generated by the combination of a strong acid $HN{O_3}$​ and a strong base $NaOH$. So the aqueous solution of $NaN{O_3}$ will consists of one mole of $NaOH$ and one mole of $HN{O_3}$ and will be neutral in nature and $pH$ is $7$.

So the correct answer is B.

Note:
Unlike $pH$ the hydroxide ion concentration is represented as $pOH$. Actually the sum total of $pH$ and $pOH$ is equal to $14$. Both of them can be used to determine the acidity or basicity of a substance in aqueous solution.