11.

At 25°C, the solubility product of Mg(OH)₂ is 1.0 × 10^–11. At which pH, will Mg²⁺ ions start precipitating in the form of Mg(OH)₂ from a solution of 0.001 M Mg²⁺ ions?

• 9

• 10

• 11

• 11

For a particular reversible reaction at temperature T, ΔH and ΔS were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when 

• T_e>T

• T >T_e

• T_e is 5 times T

• T_e is 5 times T

The time for half life period of a certain reaction A → Products is 1 hour. When the initial concentration of the reactant ‘A’ is 2.0 mol L^–1, how much time does it take for its concentration to come from 0.50 to 0.25 mol L^–1 if it is a zero order reaction?

• 1 h 

• 4 h 

• 0.25 h 

• 0.25 h 

A solution containing 2.675 of CoCl₃. 6NH₃(molar mass = 267.5 g mol^–1) is passed through a cation exchanger. The chloride ions obtained is solution was treated with excess of AgNO₃ to give 4.78 g of AgCl (molar mass = 143.5 g mol^–1 ). The formula of the complex is
(At. mass of Ag = 108 u)

• [Co(NH₃)₆]Cl₃

• [CoCl₂(NH₃)₄]Cl

• [CoCl₃(NH₃)₃]

• [CoCl₃(NH₃)₃]

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water (ΔT_f), when 0.01 mol of sodium sulphate is dissolved in 1 kg of water, is (K_f = 1.86 K kg mol^–1).

• 0.0372 K

• 0.0558 K

• 0.0744 K

• 0.0744 K

29.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl’s method and the evolved ammonia was absorbed in 20 mL of 0.1 M HCl solution. The excess of the acid required 15 mL of 0.1 M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is

• 59.0

• 47.4

• 23.7

• 23.7

Which one of the following has an optical isomer?

• [Zn(en)(NH₃)₂]²⁺

• [Co(H₂O)₄(en)]³⁺

• [Co(en)₃]³⁺

• [Co(en)₃]³⁺

On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 k_Pa respectively.Vapour pressure of the solution obtained by mixing 25.0 g of heptane and 35 g of octane will be (molar mass of heptane = 100 g mol^–1 and of octane =114 g mol^–1)

• 144.5 kPa

• 72.0 kPa

• 36.1 kPa

• 36.1 kPa

The edge length of a face centred cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is 

• 144 pm

• 288 pm

• 398 pm

• 398 pm

The Gibbs energy for the decomposition of Al₂O₃ at 500°C is as follows

The potential difference needed for electrolytic reduction of Al₂O₃ at 500°C is at least

• 4.5 V

• 3.0 V

• 2.5 V

• 2.5 V