Problem 56
From separate solutions of four sodium salts NaW, NaX, NaY and \(\mathrm{NaZ}\) had \(\mathrm{pH} 7.0,9.0,10.0\) and \(11.0\) respectively, when each solution was \(0.1 M\), the weakest acid is : (a) HW (b) \(\mathrm{HX}\) (c) HY. (d) \(\mathbf{H Z}\)
Problem 58
\(\mathrm{pH}\) of an aqueous \(\mathrm{NaCl}\) solution at \(50^{\circ} \mathrm{C}\) should be : (a) 7 (b) \(>7\) (c) \(<7\) (d) 0
Problem 61
\(1 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{HCl}\) is added to \(999 \mathrm{~mL}\) solution of \(\mathrm{NaCl}\). The \(\mathrm{pH}\) of the resulting solution will be : (a) 7 (b) 4 (c) 2 (d) 1
Problem 62
If a salt of strong acid and weak base hydrolyses appreciably \((\alpha=0.1)\), which of the following formula is to be used to calculate degree of hydrolysis ' \(\alpha\) '? (a) \(\alpha=\sqrt{\frac{K_{w}}{K_{a} \cdot a}}\) (b) \(\alpha=\sqrt{\frac{K_{w}}{K_{b} \cdot a}}\) (c) \(\alpha=\sqrt{\frac{K_{w}}{K_{a} \cdot K_{b}}}\) (d) None of these
Problem 67
Calculate the \(\left[\mathrm{OH}^{-}\right]\) in \(0.01 M\) aqueous solution of \(\mathrm{NaOCN}\left(K_{b}\right.\) for \(\left.\mathrm{OCN}^{-}=10^{-10}\right):\) (a) \(10^{-6} \mathrm{M}\) (b) \(10^{-7} M\) (c) \(10^{-8} M\) (d) None of these
Problem 70
\(\%\) hydrolysis of \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONH}_{4}\), when \(K_{a}\left(\mathrm{CH}_{3} \mathrm{COOH}\right)=K_{b}\left(\mathrm{NH}_{4} \mathrm{OH}\right)=1.8 \times 10^{-5}\) is: (a) \(0.55\) (b) \(7.63\) (c) \(0.55 \times 10^{-2}\) (d) \(7.63 \times 10^{-3}\)
Problem 75
What will be the \(\mathrm{pH}\) and \(\% \alpha\) (degree of hydrolysis) respectively for the salt \(\mathrm{BA}\) of \(0.1 \mathrm{M}\) concentration? Given : \(K_{a}\) for \(\mathrm{H} A=10^{-6}\) and \(K_{b}\) for \(B O H=10^{-6}\) (a) \(5,1 \%\) (b) \(7,10 \%\) (c) \(9,0.01 \%\) (d) \(7,0.01 \%\)
Problem 78
What is the acidity constant for the following reaction given that the hydronium ion concentration of a \(0.04 \mathrm{M}\) solution of \(\mathrm{Ni}^{2+}\) solution of nickel(II) perchlorate is \(4.5 \times 10^{-6}\) ? $$ \mathrm{Ni}^{2+}(\text { aq. })+2 \mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{Ni}(\mathrm{OH})^{+}(a q .)+\mathrm{H}_{3} \mathrm{O}^{+}(a q) $$ (a) \(2 \times 10^{-12}\) (b) \(4 \times 10^{-6}\) (c) \(5 \times 10^{-12}\) (d) \(5 \times 10^{-10}\)
Problem 82
Which of the following is a buffer solution? (a) \(500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{CH}_{3} \mathrm{COOH}+500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{NaOH}\) (b) \(500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{CH}_{3} \mathrm{COOH}+500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{HCl}\) (c) \(500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{CH}_{3} \mathrm{COOH}+500 \mathrm{~mL}\) of \(0.2 \mathrm{~N} \mathrm{NaOH}\) (d) \(500 \mathrm{~mL}\) of \(0.2 \mathrm{~N} \mathrm{CH}_{3} \mathrm{COOH}+500 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{NaOH}\)
Problem 84
\(\mathrm{H}_{2} \mathrm{CO}_{3}+\mathrm{NaHCO}_{3}\) found in blood helps in maintaining \(\mathrm{pH}\) of the blood close to \(7.4 .\) An excess of acid entering the blood stream is removed by: (a) \(\mathrm{HCO}_{3}^{-}\) (b) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) (c) \(\mathrm{H}^{+}\) ion (d) \(\mathrm{CO}_{3}^{2-}\) ion
