Minimum pH balance is shown by aqueous solution of
(1) $ 0.1M $ $ BaC{l_2} $
(2) $ 0.1M $ $ Ba{(N{O_3})_2} $
(3) $ 0.1M $ $ BeC{l_2} $
(4) $ 0.1M $ $ Ba{(OH)_2} $

Hint :pH is a scale that is used to determine the acidity or basicity of an aqueous solution. Acidic solutions are known to have lower pH values than basic or alkaline solutions. The pH of a solution is the measure of concentration of hydrogen ions in a solution.

Complete Step By Step Answer:
In case of $ BaC{l_2} $ , the salt is formed using a strong acid that is $ HCl $ and a strong base $ Ba{(OH)_2} $ Hence, its pH would be close to $ 7 $ .It is slightly acidic.
In the case of $ Ba{(N{O_3})_2} $ , the salt is formed when a strong acid $ HN{O_3} $ and a strong base $ Ba{(OH)_2} $ combine. Hence, its pH would be close to $ 7 $ . It is slightly acidic.
In the case of $ BeC{l_2} $ , The salt is formed when a strong acid $ HCl $ and a weak base $ Be{(OH)_2} $ combine.
Hence, the solution is acidic as the pH is less than $ 7 $ .
 $ Ba{(OH)_2} $ is a strong base. Hence its Ph value will be more than seven.
Therefore, from the given solutions, aqueous solution of $ BeC{l_2} $ has minimum pH balance as it is acidic in nature.
Hence, the correct option is (3) $ 0.1M $ $ BeC{l_2} $ .

Note :
The pH scale ranges from 0 to 14. Solutions which have pH value less than $ 7 $ are said to be acidic solutions. Solutions which have pH value more than $ 7 $ are said to be basic solutions. Solutions that have pH value $ 7 $ are said to be neutral solutions. pH of a solution is equal to the negative of the logarithm to the base $ 10 $ of its hydrogen ion concentration.