Question

pH of the following solution is not affected by dilution
A. 0.01M `NaHCO_(3)^(-)`
B. 0.01 M `NaH_(2)PO_(4)`
C. 0.01 M `CH_(3)COONH_(4)`
D. All of these

Answer 1

Correct Answer - D
Aqueous solution of a salt of a weak acid and a weak base acts as a buffer solution. The pH of a buffer does not change on dilution. Thus , pH of 0.01 M `CH_(3)COONH_(4)` will not change on dilution. `HCO_(3)^(-)` ( from `NaHCO_(3)` and `H_(2)PO_(4)^(-)` ( from `NaH_(2)PO_(4))` are amphiprotic anions. The pH of solution containing amphiprotic anions do not change on dilution. Thus, all the three choices A,B and C are correct.