361.

he amount of solute (molar mass 60 g mol^-1) that must be added to 180 g of water so that the vapour pressure· of water is lowered by 10%, is

• 30g

• 60g

• 120g

• 12g

An 1% solution of KCl (I), NaCl (II), BaCl₂ (III) and urea (IV) have their osmotic pressure at the same temperature in the ascending order (molar masses of NaCl, KCl, BaCl₂ and urea are respectively 58.5, 74.5, 208.4 and 60 g.mol^-1). Assume 100% ionization of the electrolytes at this temperature.

• III < IV < I < II

• I < III < II < IV

• III < I < II < IV

• I < III < IV < II

The difference between the boiling point and freezing point of an aqueous solution containing sucrose (molecular wt = 342g mol^-1) in 100 g of water is 105.0°C. If k_f and k_b of water are 1.86 and 0.51 K kg mol^-1 respectively, the weight of sucrose in the solution is about?

• 34.2 g

• 342 g

• 7.2 g

• 72 g

The relative lowering of vapour pressure of an aqueous solution containing non-volatile solute is 0.0125. The molality of the solution is

• 0.70

• 0.50

• 0.60

• 0.80

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

• 10

• 100 T_b

• $∆$T_b

• 10 T_b

The two isomers X and Y with the formula Cr(H₂O)₅ClBr₂ were taken for experiment on depression in freezing point. It was found that one mole of X gave depression corresponding to 2 moles of particles and one mole of Y gave depression due to 3 moles of particles. The structural formulae of X and Y respectively are

• [Cr(H₂O)₄Br₂]Cl·H₂O; [Cr(H₂O)₅Cl]Br₂ 

• [Cr(H₂O)₅Cl]Br₂;[Cr(H₂O)₄ClBr]Br·H₂O

• [Cr(H₂O)₅Cl]Br₂;[Cr(H₂O)₄Br₂]Cl·H₂O

• [Cr(H₂O)₅Cl]Br₂;[Cr(H₂O)₃ClBr₂·H₂O]

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

Dry air is passed through a solution containing 10 g of a solute in 90 g of water and then through pure water. The loss in weight of solution is 2.5 g and that-of pure solvent is 0.05 g. Calculate the molecular weight of the solute.

• 50

• 180

• 102

• 25

The van't Hoff factor of BaCl₂ at 0.01 M concentration is 1.98. The percentage of dissociation of BaCl₂ at this concentration is :

• 49

• 69

• 89

• 98