Question

The correct order of increasing pH of decimolar solution of each of the following is
\[
  A.{\text{ }}N{H_4}N{O_3} < NaN{O_3} < NaHC{O_3} < N{a_2}C{O_3} \\
  B.{\text{ }}NaN{O_3} < N{H_4}N{O_3} < NaHC{O_3} < N{a_2}C{O_3} \\
  C.{\text{ }}NaN{O_3} < N{H_4}N{O_3} < N{a_2}C{O_3} < NaHC{O_3} \\
  D.{\text{ }}N{a_2}C{O_3} < NaHC{O_3} < NaN{O_3} < N{H_4}N{O_3} \\
 \]

Answer 1

Hint- In order to find the order first we will understand the basic term pH then we will proceed further by knowing that on which factors it depends and comparing the given solutions we will conclude the answer.

Complete answer:
pH: pH is a measure of the hydrogen ion concentration in solution and is also referred to as the degree of acidity or alkalinity.
As we know that \[N{H_4}N{O_3}\] is a weak base and has the $pH \leqslant 7$
Also we know that is \[NaN{O_3}\] a strong acid having the value of $pH = 7$
\[NaHC{O_3}\] is a strong base and has the value of $pH > 7$
Similarly \[N{a_2}C{O_3}\] is a strong base and has the value of $pH > 7$
But out of \[NaHC{O_3}\] and \[N{a_2}C{O_3}\] the strong base \[N{a_2}C{O_3}\] has higher pH value.
Hence, on the basis of above comparison we have the correct order of increasing pH of decimolar solution of each of the following is:
\[N{H_4}N{O_3} < NaN{O_3} < NaHC{O_3} < N{a_2}C{O_3}\]
So, option A is the correct option.

Note- pH is a measure of the acidic or basic (alkaline) nature of a solution (concentration of the hydrogen ion [H+] activity in a solution determines the pH). The pH scale ranges from 0 to 14, which is the most acidic, a pH of 7 is neutral, and 14 is the most alkaline.