31.

On the basis of standard electrode potential of redox couples given below, find out which of the following is the strongest oxidising agent.

(E$°$ values : Fe³⁺ | Fe²⁺ = +0.77 V; I_2(s) | I^- = +0.54 V; Cu²⁺ | Cu = +0.34 V; Ag⁺ | Ag = +0.80 V)

• Fe³⁺

• I_2(s)

• Cu²⁺

• Ag⁺

The depression in freezing point of 0.1 M aqueous solutions of HCl, CuSO₄ and K₂SO₄ are in the ratio

• 1 : 1 : 1.5

• 1 : 2 : 3

• 1 : 1 : 1

• 2 : 4 : 3

The chemical reaction, 2O₃ $\to$ 3O₂ proceeds as follows:

Step 1 : O₃ $\rightleftharpoons$ O₂ + O  ...(fast)

Step 2 : O + O₃ $\to$2O₂ ...(slow)

The rate law expression should be

• r = k' [O₃][O₂]

• r = k'[O₃]²[O₂]^-1

• r = k'[O₃]²

• unpredictable

The coagulation of 200 mL of a positive colloid took place when 0.73 g HCl was added to it without changing the volume much. The flocculation value of HCl for the colloid is

• 100

• 36.5

• 0.365

• 150

ZnO is white when cold and yellow when heated. It is due to the development of

• Frenkel defect

• metal excess defect

• Schottky defect

• metal deficiency defect.

Which of the following pairs of substances cannot exist together in solution?

• Na₂CO₃ + NaOH

• NaHCO₃ + Na₂CO₃

• NaHCO₃ + NaOH

• NaOH + HCl

Among the following, the compound that is both paramagnetic and coloured is

• K₂Cr₂O₇

• (NH₄)₂[TiCl₆]

• VOSO₄

• K₃[Cu(CN)₄]

Assertion : If standard reduction potential for the reaction Ag⁺ + e^- $\to$ Ag is 0.80 volt, then for the reaction 2Ag⁺ + 2e^- $\to$ 2Ag, it will be 1.60 volt.

Reason: If concentration of Ag⁺ ions is doubled, the standard electrode potential is also doubled.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : Hydrides of group-16 elements show volatility in the order :

H₂O > H₂S > H₂Se > H₂Te

Reason : Electronegativity of group-16 elements increases down the group from oxygen to tellurium

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false.

• If both assertion and reason are false

Assertion : Equivalent weight of NH, in the reaction, N, $\to$ NH₃ is 17/3 while that of N₂ is 28/6.

Reason : Equivalent weight = $\frac{\mathrm{Molecular} \mathrm{weight}}{\mathrm{Number} \mathrm{of} {\mathrm{e}}^{-} \mathrm{lost} \mathrm{or} \mathrm{gained} \mathrm{per} \mathrm{mole}}$

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false