Solutions

pA and pB are the vapour pressures of pure liquid components, A and B, respectively of an ideal binary solution. If xA represents the mole fraction of component A, the total pressure of the solution will be

1. pA + xA (pB - pA )
2. pA + xA (pA - pB )
3. pB + xA (pB - pA )
4. pB + xA (pA - pB )

A 0.1 molal aqueous solution of a weak acid is 30% ionized. If Kf for water is 1.86 C/m, the freezing point of the solution will be

1. -0.18 C
2. -0.54 C
3. -0.36 C
4. -0.24 C

200 mL of an aqueous solution of a protein contains its 1.26 g. The osmotic pressure of this solution at 300 K is found to be 2.57 10-3 bar. The molar mass of protein will be (R = 0.083 L bar mol-1 K-1)

1. 51022 g mol-1
2. 122044 g mol-1
3. 31011 g mol-1
4. 61038 g mol-1

The freezing point depression constant for water is 1.86 C m-1. If 5.00 g Na2SO4 is dissolved in 45.0 g H2O, the freezing point is changed by -3.82 C. Calculate the van't Hoff factor for Na2SO4.

1. 2.05
2. 2.63
3. 3.11
4. 0.381

The van't Hoff factor i for a compound which undergoes dissociation in one solvent and association in other solvent is respectively

1. less than one and greater than one
2. less than one and less than one
3. greater than one and less than one
4. greater than one and greater than one

An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase?

1. Addition of NaCl
2. Addition of Na2SO4
3. Addition of 1.00 molal KI
4. Addition of water

A solution of sucrose (molar mass = 342 g mol-1) has been prepared by dissolving 68.5 g of sucrose in 1000 g of water. The freezing point of the solution obtained will be (Kf for water = 1.86 K kg mol-1)

1. -0.372 C
2. -0.520 C
3. +0.372 C
4. -0.570 C

A 0.0020 m aqueous solution of an ionic compound [Co(NH3)5(NO2)]Cl freezes at -0.00732 C. Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be (Kf = 1.86 C/m)

1. 3
2. 4
3. 1
4. 2

0.5 molal aqueous solution of a weak acid (HX) is 20% ionised. If Kf for water is 1.86 K kg mol-1, the lowering in freezing point of the solution is

1. 0.56 K
2. 1.12 K
3. -0.56 K
4. -1.12 K

During osmosis, flow of water through a semipermeable membrane is

1. from solution having lower concentration only
2. from solution having higher concentration only
3. from both sides of semipermeable membrane with equal flow rates
4. from both sides of semipermeable membrane with unequal flow rates.

A solution of acetone in ethanol

1. obeys Raoult's law
2. shows a negative deviation from Raoult's law
3. shows a positive deviation from Raoult's law
4. behaves like a near ideal solution.

1.00 g of a non-electrolyte solute (molar mass 250 g mol-1) was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kf of benzene is 5.12 K kg mol-1, the freezing point of benzene will be lowered by

1. 0.2 K
2. 0.4 K
3. 0.3 K
4. 0.5 K

A solution containing 10 g per dm3 of urea (molecular mass = 60 g mol-1) is isotonic with a 5% solution of a nonvolatile solute. The molecular mass of this nonvolatile solute is

1. 200 g mol-1
2. 250 g mol-1
3. 300 g mol-1
4. 350 g mol-1

The mole fraction of the solute in one molal aqueous solution is

1. 0.009
2. 0.018
3. 0.027
4. 0.036

The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mole of Q would be

1. 72 torr
2. 140 torr
3. 68 torr
4. 20 torr

A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressures of the pure hydrocarbons at 20 are 440 mm Hg for pentane and 120 mm Hg for hexane. The mole fraction of pentane in the vapour phase would be

1. 0.200
2. 0.549
3. 0.786
4. 0.478

A solution of urea (mol. mass 60 g mol-1) boils at 100.18 at the atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512 K kg mol-1 respectively, the above solution will freeze at

1. 0.654
2. -0.654
3. 6.54
4. -6.54

Formation of solution from two components can be considered as (i) Pure solvent separated solvent molecules, H1 (ii) Pure solute separated solute molecules, H2 (iii) Separated solvent and solute molecules solution, H3 Solution so formed will be ideal if

1. Hsoln = H1 + H2 + H3
2. Hsoln = H1 + H2 - H3
3. Hsoln = H1 - H2 - H3
4. Hsoln = H3 - H1 - H2

A solution containing components A and B follows Raoult's law when

1. A-B attraction force is greater than A-A and B-B
2. A-B attraction force is less than A-A and B-B
3. A-B attraction force remains same as A-A and B-B
4. volume of solution is different from sum of volumes of solute and solvent

A solution contains non-volatile solute of molecular mass M2. Which of the following can be used to calculate the molecular mass of solute in terms of osmotic pressure?

1. M2 = ( m2 )VRT
2. M2 = ( m2V ) RT
3. M2 = ( m2V ) RT
4. M2 = ( m2V ) RT

Pure water can be obtained from sea water by

1. centrifugation
2. plasmolysis
3. reverse osmosis
4. sedimentation

From the colligative properties of solution, which one is the best method for the determination of molecular weight of proteins and polymers?

1. Osmotic pressure
2. Lowering in vapour pressure
3. Lowering in freezing point
4. Elevation in boiling point