At what pH does Mg(OH)₂ start to precipitate from a solution with 0.10 M Mg²⁺ ions, given that the Ksp of Mg(OH)₂ is 1 × 10⁻¹¹?

1. 3

2. 6

3. 9

4. 11

50 litres of 0.1 M HCl are mixed with 50 litres of 0.2 M NaOH. The pH of the resulting solution will be:

1. 12.70

2. 12.34

3. 8.7

4. 4.2

The pH of a 0.05 M aqueous solution of diethylamine is 12. Its K_b value will be:

1. $2\times {10}^{-3}$

2. $2.5\times {10}^{-3}$

3. $3\times {10}^{-3}$

4. $4.5\times {10}^{-3}$

K_a for HCN is $5\times {10}^{-10}$ at $25°\mathrm{C}$. For maintaining a constant pH of 9, the volume of 5 M KCN solution required to be added to 10 mL of 2 M HCN solution is-

1. 2 mL

2. 3 mL

3. 4.2 mL

4. 5.6 mL

The approximate pH of a solution formed by mixing equal volumes of solutions of 0.1 M sodium propionate and 0.1 M propanoic acid (the dissociation constant of propanoic acid is $1.3\times {10}^{-5} \mathrm{mol} {\mathrm{dm}}^{-3}$) will be

1. 2.45

2. 4.89

3. 5.98

4. 6.89

The dissociation constant of acetic acid is \(1 . 6 \times \left(10\right)^{- 5}\). The degree of dissociation \(\left(\right. \alpha \left.\right)\) of 0.01 M acetic acid in the presence of 0.1 M HCl is equal to:
1. \(1.6 \times 10^{-3}\)
2. \(1.6 \times 10^{-1}\)
3. \(1.6 \times 10^{-6}\)
4. \(1.6 \times 10^{-4}\)

If the equilibrium constant of the reaction of weak acid HA with strong base is 10⁹, then pH of 0.1 M NaA is

1. 3

2. 9

3. 7

4. 6

If Ksp of Al(OH)₃ is $1.0\times {10}^{-15} \mathrm{M}.$ Find at what pH does $1.0\times {10}^{-3} \mathrm{M}$ Al³⁺ precipitate on the addition of buffer of NH₄Cl and NH₄OH solution.

1. 10

2. 10.5

3. 11

4. 12

The solubility of CaF₂ in water at 298 K is $1.7\times {10}^{-3}$ gm per 100 cm³. The solubility product of CaF₂ at 298 K is

1. $4.14\times {10}^{-11}$

2. $4.14\times {10}^{11}$

3. $4.14\times {10}^{-6}$

4. $4.14\times {10}^6$

A solution of monoprotic weak acid has acidity constant K_a the minimum intial concentration 'c' in terms of K_a, such that the concentration of the undissociated acid can be equated to 'c' within a 10% limit of error, would be

1. 70 K_a

2. 90 K_a

3. 50 K_a

4. 30 K_a