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

Hint: 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^ + }] $