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Solutions - Class 12 MCQ


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30 Questions MCQ Test - Solutions

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Solutions - Question 1

When a crystal of the solute is introduced into a super saturated solution of the solute:    

Detailed Solution for Solutions - Question 1

Super saturated state is a meta stable state.

Solutions - Question 2

Equimolal solutions of A and B show depression in freezing point in the ratio 2 : 1.

A remains in its normal state in solution.             

B will be ...in solution    

Detailed Solution for Solutions - Question 2

 B should associate to show higher ΔT

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Solutions - Question 3

On the basis of intermolecular forces predict the correct order of decreasing boiling points of the compounds:    

Detailed Solution for Solutions - Question 3

Alcohol involves H-bonding; also mol.wt. of CH4 > mol. wt. of H2. Greater is molecular weight of covalent
compound,higher is its b.p.

Solutions - Question 4

At high altitudes the boiling of water occurs at low temperature beacuse:    

Detailed Solution for Solutions - Question 4

The boiling occurs at lower temperature, if atmospheric pressure is lower than 76 cm Hg.

Solutions - Question 5

The correct relationship between the boiling points of very dilute solutions of AICI3 (t1) and CaCI2 (t2), having the same molar     

concentration, is

Detailed Solution for Solutions - Question 5

AICI3 furnishes more ions than CaCl2 and thus, show higher b.p.

Solutions - Question 6

Two solutions of KNO3 and CH3COOH are prepared separately. Molarity of both is 0.1 M and osmotic pressure are P1 and Prespectively. The correct relationship between the osmotic pressures is:    

Detailed Solution for Solutions - Question 6

KNO3 is 100% ionized while CH3COOH is weak electrolyte.

Solutions - Question 7

The spontaneous movement of solute particles from a more concentrated solution is called:    

Detailed Solution for Solutions - Question 7

Follow definition of diffusion.

Solutions - Question 8

The value of Kf  for water is 1.860, calculated from glucose solution. The value of Kf for water calculated for NaCI solution will be:    

Detailed Solution for Solutions - Question 8

Kf is characteristic constant for given solvent.

Solutions - Question 9

Molal elevation constant of a liquid is:    

Detailed Solution for Solutions - Question 9

Solutions - Question 10

Binary liquid solutions which exhibit negative deviations from Raoult’s law boil at temperature...than the expected value:    

Detailed Solution for Solutions - Question 10

Liquid mixtures showing negative deviations from Raoult’s law posses higher b.p. , as they have stronger intermolecular forces

Solutions - Question 11

Which pair shows a contraction in volume on mixing along with evolution of heat:    

Detailed Solution for Solutions - Question 11

Each system is non-ideal and shows ΔHmix <0.

Solutions - Question 12

Which characterises the weak intermolecular force of attraction in a liquid?    

Detailed Solution for Solutions - Question 12

Weaker are the intermolecular forces of attractions, more is the tendency for evaporation, more is vapour pressure

Solutions - Question 13

During osmosis, flow of water through a semipermeable membrane is:    

Detailed Solution for Solutions - Question 13

During osmosis, the flow of water through a semi-permeable membrane is from a solution having lower concentration only.

Solutions - Question 14

Which aqueous solution has minimum freezing point?    

Detailed Solution for Solutions - Question 14

for solute AxBy; α is degree of ionization. Colligative properties are osmotic pressure,lowering in vapour
pressure,elevation in b.p. and depression in f.p.

Solutions - Question 15

An aqueous solution is 1.0 molal in KI. Which undergoes dissociation in one solvent and association in other solvent is  respectively:    

Solutions - Question 16

An aqueous solution is 1.0 molal in KI,which change will cause the vapour pressure of solution to increase?    

Detailed Solution for Solutions - Question 16

Ps ∞ mole fraction of solvent.

Solutions - Question 17

The plots of   (where XA and YA are the mole fraction of liquid A in liquid and vapour phase respectively) is linear with slope and intercepts respectively:

Detailed Solution for Solutions - Question 17

or y = mx + C

∴ Slope = m =

Solutions - Question 18

At 400C, the vapour pressure (in torr) of methyl alcohol (A) and ethyl alcohol (B) solution is represnted by:
P = 120 XA + 138; where XA is mole fraction of methyl alcohol. The value of lim 

Detailed Solution for Solutions - Question 18

If XA = 0, then pure If XA = 1, then pure A   120+138=258 

Solutions - Question 19

Osmotic pressure of blood is 7.65 atm at 310 K. An aqueous solution of glucose that will be isotonic with blood is ...wt./vol.

Detailed Solution for Solutions - Question 19

πV = nST for glucose and blood : If isotonic πglucose = πblood;

Solutions - Question 20

Dry air was passed successively through a solution of 5 g of a solute in 180 g of water and then through pure water. Theloss in weight of solution was 2.50 g and that of pure solvent 0.04 g. The molecular weight of the solute is:

Detailed Solution for Solutions - Question 20

P0-Ps  loss in weight of water chamber and Ps loss in wt. of solution chamber.

∴m=31.25

Solutions - Question 21

Solute A is a ternary electrolyte and solute B is non-electrolyte. If 0.1 M solution of solute B produces an osmotic pressureof 2P, then 0.05 M solution A at the same temperature will produce an osmotic pressure equal to:

Detailed Solution for Solutions - Question 21

For ternary electrolyte;
            P1 = iCST = 0.05 x 3 x S x T;
        For B; 2P = 0.1 x SxT;
          ∴  P1 = 3P

Solutions - Question 22

the molal elevation constant for water is 0.52 K molality-1. The elevation caused in the boiling point of water by dissolving0.25 mole of a non-volatile solute in 250 g of water will be:

Detailed Solution for Solutions - Question 22

Solutions - Question 23

Insulin (C2H10O5)n is dissolved in a suitable solvent and the osmotic pressure (p) of solutions of various concentrations(g /cm3) C is measured at 200C. The slope of a plot of π against C is found to be 4.65 x 10-3. The molecular weight of theinsulin is:     

Detailed Solution for Solutions - Question 23

The plots of π vs.c(g/cm3) have slope=

Solutions - Question 24

20 g of a binary electrolyte (mol.wt. = 100) are dissolved in 500 g of water. The freezing point of the solution is -0.740C, Kf= 1.86 K molality -1. The degree of ionization of the electrolyte is :    

Detailed Solution for Solutions - Question 24

    

Solutions - Question 25

A solution containing 4 g of polyvinyl chloride in 1 litre of dioxane was found to have an osmotic pressure of 6 x 10-4 atm at 300 K. The molecular mass of the polymer is:    

Detailed Solution for Solutions - Question 25

m=1.64*105

Solutions - Question 26

A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressures of pure hydrocarbons at 200C are 440 mm Hg for pentane and 120 mm Hg for hexane. The mole fraction of pentane in vapour phase would be:    

Detailed Solution for Solutions - Question 26

Solutions - Question 27

An aqueous solution freezes at -0.1860C (Kf = 1.860; Kb= 0.5120). What is the elevation in boiling point?

Detailed Solution for Solutions - Question 27

 

Solutions - Question 28

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

Detailed Solution for Solutions - Question 28

= 48 + 24 = 72 torr

Solutions - Question 29

A 0.0020 m aqueous solution of an ionic compound Co(NH3)5(NO2)CI freezes at -0.007320C. Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be :(Kf = + 1.860C/m)    

Detailed Solution for Solutions - Question 29

0.00732 = i x 1.86 x 0.002
∴ i = 1.96 = 2

Solutions - Question 30

Which of the given solutions has highest asmotic pressure?    

Detailed Solution for Solutions - Question 30

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