The relative lowering of vapour pressure of a dilute aqueous solution containing nonvolatile solute is 0.0125. The molality of the solution is about

• 0.70

• 0.50

• 0.90

• 0.80

If the elevation in boiling point of a solution of 10g of solute (mol. wt. = 100) in 100g of water is ΔT_b,  the ebullioscopic constant of water is 

• 100T_b

• ΔT_b

• 10T_b

• 10

An alloy of Pb-Ag weighing 1.08g was dissolved in dilute HNO₃ and the volume made to 100 mL. A silver electrode was dipped in the solution and the emf of the cell set up Pt(s), H₂(g)|H⁺(1M) || Ag⁺(aq)|Ag(s) was 0.62V. If E°_cell= 0. 80V what is the percentage of Ag in the alloy? [At 25°C, RT IF= 0.06].

• 50

• 1

• 10

• 25

The standard oxidation potentials of Zn, Cu, Ag and Ni electrodes are +0.76, 0.34, - 0.80 and +0.25 V respectively. Which of the following reaction will provide maximum voltage?

• Cu + 2Ag⁺(aq) → Cu⁺² (aq) +2Ag

• Zn + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag

• H₂ + Ni²⁺ (aq) → 2H⁺(aq) + Ni

• Zn + Cu²⁺(aq) → Zn²⁺(aq) + Cu