Q 1 :    

Given below are two statements:

Statement (I) : A Buffer solution is the mixture of a salt and an acid or a base mixed in any particular quantities.

Statement (II) : Blood is naturally occurring buffer solution whose pH is maintained by ${\mathrm{H}}_2{\mathrm{CO}}_3/{\mathrm{HCO}}_3^{-}$ concentrations.

In the light of the above statements, choose the correct answer from the options given below.               [2024]

• Both Statement I and Statement II are false

   

• Statement I is true but Statement II is false

   

• Statement I is false but Statement II is true

   

• Both Statement I and Statement lI are true

   

Q 2 :    

The pH of an aqueous solution containing 1M benzoic acid $({\mathrm{pK}}_{\mathrm{a}}=4.20)$ and 1M sodium benzoate is 4.5. The volume of benzoic acid solution in 300 mL of this buffer solution is ________ mL. (given: log 2 = 0.3)              [2024]

Q 3 :    

Only litre buffer solution was prepared by adding 0.10 mol each of ${\mathrm{NH}}_3$ and ${\mathrm{NH}}_4\mathrm{Cl}$ in deionised water. The change in pH on addition of 0.05 mol of HCl to the above solution is ____ $\times {10}^{-2}$, (Nearest integer)                          

(Given : $p{K}_b$ of ${\mathrm{NH}}_3$ = 4.745 and ${\log }_{10}$ 3 = 0.477)                              [2025]