Which of the following statements is correct?

I. The pH of $1.0\times {10}^{-8 }\mathrm{M}$ solution of HCl is 8

II. The conjugate base of ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$ is ${\mathrm{HPO}}_4^{2-}$

III. Autoprotolysis constant of water increases with temperature

IV. When a solution of a weak monoprotic acid is titrated against a strong base at half neutralization point, pH = (1/2) pKa.

1. II, III

2. I, II, III

3. III, IV

4. II, III, IV

The solubility of ${\mathrm{A}}_2{\mathrm{X}}_3$ is y mol dm^-3. Its solubility product is

1. $6 {\mathrm{y}}^4$

2. $64 {\mathrm{y}}^4$

3. $36 {\mathrm{y}}^5$

4. $108 {\mathrm{y}}^5$

If ${\mathrm{pK}}_{\mathrm{b}}$ for fluoride ion at $25°\mathrm{C}$ is 10.83, the ionization constant of hydrofluoric acid at this temperature is

1. $1.74\times {10}^{-5}$

2. $3.52\times {10}^{-3}$

3. $6.75\times {10}^{-4}$

4. $5.38\times {10}^{-2}$

The pK_a of HCN is 9.30. The pH of a solution prepared by mixing 2.5 moles of KCN and 2.5 moles of HCN in water and making up the total volume to 500 ml will be:

What is the decreasing order of strength of the bases?

${\mathrm{OH}}^{-}, {\mathrm{NH}}_2^{-}, \mathrm{H}-\mathrm{C}\equiv {\mathrm{C}}^{-} \mathrm{and} {\mathrm{CH}}_3-{\mathrm{CH}}_2^{-}?$

1. ${\mathrm{CH}}_3-{\mathrm{CH}}_2^{-}>{\mathrm{NH}}_2^{-}>\mathrm{H}-\mathrm{C}\equiv {\mathrm{C}}^{-}>{\mathrm{OH}}^{-}$

2. $\mathrm{H}-\mathrm{C}\equiv {\mathrm{C}}^{-}>{\mathrm{CH}}_3-{\mathrm{CH}}_2^{-}>{\mathrm{NH}}_2^{-}>{\mathrm{OH}}^{-}$

3. ${\mathrm{OH}}^{-}>{\mathrm{NH}}_2^{-}>\mathrm{H}-\mathrm{C}\equiv {\mathrm{C}}^{-}>{\mathrm{CH}}_3-{\mathrm{CH}}_2^{-}$

4. ${\mathrm{NH}}_2^{-}>\mathrm{H}-\mathrm{C}\equiv {\mathrm{C}}^{-}>{\mathrm{OH}}^{-}>{\mathrm{CH}}_3-{\mathrm{CH}}_2^{-}$

The following equilibrium is established when hydrogen chloride is dissolved in acetic acid

$\mathrm{HCl}+{\mathrm{CH}}_3\mathrm{COOH}\leftrightarrow {\mathrm{Cl}}^{-}+{\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+}$

The set that characterizes the conjugate acid base pair is

1. $(\mathrm{HCl}, {\mathrm{CH}}_3\mathrm{COOH}) \mathrm{and} ({\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+},\hspace{0.17em}{\mathrm{Cl}}^{-})$

2. $(\mathrm{HCl}, {\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+}) \mathrm{and} (\mathrm{HCl},\hspace{0.17em}{\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+}) \mathrm{and} ({\mathrm{CH}}_3\mathrm{COOH}, {\mathrm{Cl}}^{-})$

3. $({\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+}, \mathrm{HCl}) \mathrm{and} ({\mathrm{Cl}}^{-}, {\mathrm{CH}}_3\mathrm{COOH})$

4. $(\mathrm{HCl}, {\mathrm{Cl}}^{-}) \mathrm{and} ({\mathrm{CH}}_3{{\mathrm{COOH}}_2}^{+}, {\mathrm{CH}}_3\mathrm{COOH})$

Which of the following is an example of a reversible reaction?
1. \(\small{KNO_3(aq) + NaCl(aq) \rightleftharpoons KCl(aq) + NaNO_3(aq)}\)
2. \(\small{2Na(s) + H_2O(l) \rightleftharpoons 2NaOH(aq) + H_2(g)}\)
3. \(\small{AgNO_3(aq) + NaCl(aq) \rightleftharpoons AgCl(s) + NaNO_3(aq)}\)
4. \(\small{Pb{(NO_3)}_2(aq) + 2NaI(aq) \rightleftharpoons PbI_2(s) + 2NaNO_3(aq)}\)

A certain weak acid has a dissociation constant of $1.0\times {10}^{-4}.$ The equilibrium constant for its reaction with a strong base is

1. $1.0\times {10}^{10}$

2. $1.0\times {10}^{14}$

3. $1.0\times {10}^{-10}$

4. $1.0\times {10}^{-4}$

The precipitate of CaF₂ $({\mathrm{K}}_{\mathrm{sp}}=1.7\times {10}^{-10})$ is obtained when equal volumes of the following are mixed

1. ${10}^{-2} \mathrm{M} {\mathrm{Ca}}^{2+}+{10}^{-3} {\mathrm{MF}}^{-}$

2. ${10}^{-3} \mathrm{M} {\mathrm{Ca}}^{2+}+{10}^{-5} {\mathrm{MF}}^{-}$

3. ${10}^{-4} \mathrm{M} {\mathrm{Ca}}^{2+}+{10}^{-4} {\mathrm{MF}}^{-}$

4. ${10}^{-5} \mathrm{M} {\mathrm{Ca}}^{2+}+{10}^{-3} {\mathrm{MF}}^{-}$

In the exothermic reaction of oxidizing SO₂ by O₂ to SO₃, what factors determine the maximum yield of SO₃?