Question

Which of the following has a maximum of $pH$ ?
(A) $0.01M$ ${H_2}S{O_4}$
(B) $0.01M$ $HCl$
(C) $0.01M$ $Ca{(OH)_2}$
(D) $0.01M$ $NaOH$

Answer 1

In the above question we are asked to find out which of the following options has a maximum $pH$ . A compound having a maximum $pH$ can also be stated as a strong base that is a compound which has a higher concentration of $O{H^ - }$ ions.

Complete step by step solution:
$pH$ states the potential or power of hydrogen. Acidic solution contains higher concentration of ${H^ + }$ ions and are considered to have lower $pH$ values, on the other hand, basic solution contains higher concentration of $O{H^ - }$ ions and are considered to have higher $pH$ values. Now $pH$ scale is marked from 1-14, a compound having $pH$ marked below 7 is considered to be acidic, $pH$ marked above is considered basic and $pH$ marked exactly 7 is considered neutral compound. Lesser the marking of a compound on $pH$ scale, more acidic is the compound, greater the marking of a compound on $pH$ scale, more basic is the compound.
In the above question, we are provided with four options having the same molar concentration, that is $0.01M$ . Options A and B are ${H_2}S{O_4}$ and $HCl$ which are both strong acids and therefore they have the least value of $pH$ according to the above-given explanation. In option C and D we are provided with two bases $Ca{(OH)_2}$ and $NaOH$ , since the calcium hydroxide molecule can donate two hydroxide ions then it has a higher concentration of $O{H^ - }$ ions and hence have the maximum $pH$ value.

Note:
If you are provided with the concentration of ${H^ + }$ ions in a solution as moles per litre that is the molarity of the solution, you can find out the $pH$ of the solution by using the formula $pH = - \log [{H^ + }]$