Question

The pH of ${10^{ - 3}}$ $M{H_2}S{O_4}$ will be almost:
A. >7
B. <7
C. 6
D. 0

Answer 1

The pH scale is logarithmic meaning that an increase or decrease of an integer value changes the concentration by tenfold. It is common that the pH scale is argued to range from 0-14 or perhaps 1-14, but neither is correct. The pH range does not have an upper or lower bound, since as defined above, the pH is an indication of concentration of ${H^ + }$.

Complete step by step answer:
If $pH > 7$ the solution is basic. The pOH should be looked at from the perspective of $O{H^ - }$ instead of ${H^ + }$. Whenever the value of pOH is less than 7, then it is considered basic and therefore there are more $O{H^ - }$ than ${H^ + }$ in the solution.
At pH 7, the substance or solution is at neutral and means that the concentration of ${H^ + }$ and $O{H^ - }$ ion is the same.
If $pH < 7$ the solution is acidic. There are more ${H^ + }$ than $O{H^ - }$ in an acidic solution. The pH scale does not have an upper or lower bound.
Here we find out the pH of Sulphuric acid which reaction is given below:
${H_2}S{O_4} \rightleftharpoons 2{H^ + } + SO_4^{ - 2}$
Sulphuric acid is dibasic acid and it gives two ${H^ + }$ atoms in solution.
Hence, $[{H^ + }] = 2 \times 0.001M$
$pH = - \log (2 \times 0.001)$
=2.69
As we see the calculation, the pH of Sulphuric acid is <7.

Therefore, option (B) is the correct answer.

Note: pH scale is using to identify the acidic and basic solution. If pH is greater than 7, it means the solution is basic and if the pH value is less than of, which means the solution is basic. The range of pH scale is 0-14. If the solution contains pH value is 7, it means that solution is neutral. For example, the pH value of water is 7, so water is a neutral solution.