Find the molar heat of solution of PbI₂ given that its solubility product is 7.47 × 10⁻⁹ at 15°C
 and 1.39 × 10⁻⁸ at 25°C.
(Given,  log 1.86 = 0.2695)

1.	44.29 kJ/mol	2.	46.25 kJ/mol
3.	29.37 kJ/mol	4.	21.15 kJ/mol

Which of the following compounds are in the correct sequence in terms of relative basic strength?

1. \(C_{2} H_{5} O^{-} > CH \equiv C^{-} > \left(OH\right)^{-}\)

2. \(CH \equiv C^{-} >(OH)^{-} > C_{2} H_{5} O^{-}\)

3. \(CH \equiv C^{-} > C_{2} H_{5} O^{-} > \left(OH\right)^{-}\)

4. \(C_{2} H_{5} O^{-} > \left(OH\right)^{-} > CH \equiv C^{-}\)

The concentration of CH₃COOH that will have the same [H⁺] as obtained from 10^-2 M HCOOH, is-

$\left(\mathrm{Ka}\right({\mathrm{CH}}_3\mathrm{COOH})={10}^{-5},$ $\mathrm{Ka}\left(\mathrm{HCOOH}\right)={10}^{-4})$

1. 10 M

2. 5 M

3. 10^-1 M

4. 6 M

What happens when NH₄Cl is added to an aqueous solution of NH₄OH?

1. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions decreases.

2. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions increases.

3. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions as well as concentration $\left[{\mathrm{OH}}^{-}\right]$ ions increase.

4. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions decreases.

Find the change in pH when 500 mL of 0.2 M HCl is mixed with 500 mL of 0.2 M CH₃COOH, and 25 mL of this mixture is titrated with 0.1 M NaOH, up to the stage where HCl is just completely neutralized (Ka for acetic acid = 2.0 × 10⁻⁵).

When 60 ml of 0.1 M $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$ is mixed with 40 ml of 0.125 M ${\mathrm{Na}}_2{\mathrm{CO}}_3$, ${\mathrm{CaCO}}_3$ precipitates. If K_sp of ${\mathrm{CaCO}}_3$ is $5\times {10}^{-9}<mspace\; width="1em"></mspace>$, then $\left[{\mathrm{CO}}_3^{2-}\right]$ in the resulting solution is :

1. \(5 \times 10^{-8} ~\text M\)
2. \(5 \times 10^{-9} ~\text M\)
3. \(5 \times 10^{-6} ~\text M\)
4. \(5 \times 10^{-7} ~\text M\)

100 ml of 0.3 M NH₄OH is mixed with 100 ml of 0.2 M NaOH. K_b NH₄OH is $1.8\times {10}^{-5}$. The degree of dissociation of NH₄OH is:

1. $1.02\times {10}^{-2}$

2. $1.8\times {10}^{-5}$

3. $1.8\times {10}^{-4}$

4. $1.02\times {10}^{-4}$

Find the rate constant (in L mol⁻¹ s⁻¹) for proton transfer from water to NH₃ at 25°C, given:

Ionization constant of NH₄⁺ in water = 5.6 × 10⁻¹⁰
Rate constant for NH₄⁺ + OH⁻ → NH₃ + H₂O = 3.4 × 10¹⁰ L mol⁻¹ s⁻¹
1. 6.07 × 10⁻⁵
2. 6.07 × 10⁵
3. 3.07 × 10⁻³
4. 3.07 × 10⁻⁴

The equilibrium constant of ${\mathrm{NH}}_4^{+}$ to NH₃ and H⁺ is 10^-10. The rate constant for ${\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}\to {\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}$ is 10¹⁰.
The rate constant for ${\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}$ is:

1. ${10}^5$

2. ${10}^{20}$

3. ${10}^8$

4. ${10}^9$

Find the change in pH required to convert an indicator (Ka = 3 × 10⁻⁵) from a state where 75% is in acid form (red) to a state where 75% is in base form (blue), given log 3 = 0.4770:

1. 0.95

2. 2.3

3. 0.75

4. 5.0