41.

An aqueous solution contains an unknown concentration of Ba²⁺. When 50 mL of a 1 M solution of Na₂SO₄ is added, BaSO₄ just begins to precipitate. The final volume is 500 mL. The solubility product of BaSO₄ is 1 x 10–10. What is the original concentration of Ba²⁺?

• 1.0 x 10^–10 M

• 5 x 10^–9 M

• 2x10^–9 M

• 1.1 x 10^–9M

Assuming the compounds to be completely dissociated in aqueous solution, identify the pair of the solutions that can be expected to be isotonic at the same temperature.

• 0.01 M urea and 0.01 M NaCl

• 0.02 M NaCl and 0.01 M Na₂SO₄

• 0.03 M NaCl and 0.02 M MgCl₂

• 0.01 M sucrose and 0.02 M glucose

If $\mathrm{p}°$and p are the vapour pressure of the pure solvent and solution and n₁ and n₂ are the moles of solute and solvent respectively in the solution then the correct relation between p and p° is

• $\mathrm{p}°=\mathrm{p}\left[\frac{{\mathrm{n}}_1}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}°=\mathrm{p}\left[\frac{{\mathrm{n}}_2}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}=\mathrm{p}°\left[\frac{{\mathrm{n}}_2}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}=\mathrm{p}°\left[\frac{{\mathrm{n}}_1}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

In aqueous alkaline solution, two electrons reduction of HO${}_2^{-}$ gives

• HO^-

• H₂O

• O₂

• O${}_2^{-}$

To observe an elevation of boiling point of 0.05$°$C, the amount of a solute ( mol. wt. = 100) to be added to 100 g of water (K_b= 0.5) is

• 2g

• 0.5g

• 1g

• 0.75g

The measured freezing point depression for a 0.1 m aqueous CH₃COOH solution is 0.19°C. The acid dissociation constant K_a at this concentration will be (Given, K_f the molal cryoscopic constant = 1.86 K kg mol^-1)

• 4.76 × 10^-5

• 4 × 10^-5

• 8 × 10^-5

• 2 × 10^-5

58.4 g of NaCl and 180 g of glucose were separately dissolved in l000 mL of water. Identify the correct statement regarding the elevation of boiling point (b.p) of the resulting solutions.

• NaCl solution will show higher elevation of boiling point

• Glucose solution will show higher elevation of boiling point

• Both the solutions will show equal elevation of boiling point

• The boiling point elevation will be shown by neither of the solutions

Which of the following will show a negative deviation from Raoult's law?

• Acetone-benzene

• Acetone-ethanol

• Benzene-methanol

• Acetone-chloroform

A saturated solution of H₂S in 0.1 M HCl at 25°C contains S^2- ion concentration of 10^-23 mol L^-1. The solubility product of some sulphides are CuS = 10^-44, FeS = 10^-14, MnS = 10^-15 , CdS = 10^-25 . If 0.01 M solution of these salts in 1M HCl are saturated with H₂S, which of these will be precipitated?

• All

• All except MnS

• All except MnS and FeS

• Only CuS

If the elevation in boiling point of a solution of 10 g of solute (mol. wt. = 100) in 100 g of water is $∆{\mathrm{T}}_{\mathrm{b}}$ the ebullioscopic constant of water is

• 10

• 100 T_b

• $∆{\mathrm{T}}_{\mathbf{b}}$

• $\frac{∆{\mathrm{T}}_{\mathrm{b}}}{10}$