Chemistry 12 Chapter 2 Exemplar Solutions Question and Answer Part 3

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Question 20:

We have three aqueous solutions of labelled as ‘A’, ‘B’ and ‘C’ with concentrations and , respectively. The value of van’t Hoff factor for these solutions will be in the order______.

(i)

(ii)

(iii)

(iv)

Answer: (iii)

Question 21:

On the basis of information given below mark the correct option. Information:

(A) In bromoethane and chloroethane mixture intermolecular interactions of A–A and B–B type are nearly same as A–B type interactions.

(B) In ethanol and acetone mixture A–A or B–B type intermolecular interactions are stronger than A–B type interactions.

(C) In chloroform and acetone mixture A–A or B–B type intermolecular interactions are weaker than A–B type interactions.

(i) Solution (B) and (C) will follow Raoult’s law.

(ii) Solution (A) will follow Raoult’s law.

(iii) Solution (B) will show negative deviation from Raoult’s law.

(iv) Solution (C) will show positive deviation from Raoult’s law.

Answer: (ii)

Question 22:

Two beakers of capacity were taken. One of these beakers, labelled as “A”, was filled with water whereas the beaker labelled “B” was filled with of solution of . At the same temperature both the beakers were placed in closed containers of same material and same capacity as shown in Fig. 2.2.

Two beakers of capacity

Two Beakers of Capacity

At a given temperature, which of the following statement is correct about the vapour pressure of pure water and that of solution.

(i) Vapour pressure in container (A) is more than that in container (B).

(ii) Vapour pressure in container (A) is less than that in container (B).

(iii) Vapour pressure is equal in both the containers.

(iv) Vapour pressure in container (B) is twice the vapour pressure in container (A).

Answer: (i)

Question 23:

If two liquids A and B form minimum boiling azeotrope at some specific composition then _______________.

(i) A–B interactions are stronger than those between A–A or B–B.

(ii) Vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.

(iii) Vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution.

(iv) A–B interactions are weaker than those between A–A or B–B

Answer: (i)

Question 24:

of aqueous solution of was diluted by adding one litre of water. The molality of the resultant solution is _____________.

(i)

(ii)

(iii)

(iv)

Answer: (iv)

Question 25:

On the basis of information given below mark the correct option. Information : On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.

(i) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult’s law.

(ii) At specific composition methanol-acetone mixture forms maximum boiling azeotrope and will show positive deviation from Raoult’s law.

(iii) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult’s law.

(iv) At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show negative deviation from Raoult’s law.

Answer: (ii)

Question 26:

value for , and are and respectively.

Arrange these gases in the order of their increasing solubility.

(i)

(ii)

(iii)

(iv)

Answer: (iii)

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