Solutions Solved Examples | Chemistry for JEE Main & Advanced PDF Download

 Page 1


Solved Examples on Solutions 
JEE Mains 
Q1. 1.0 molal aqueous solution of an electrolyte ?? ?? ?? ?? is ???? % ionized. The boiling 
point of the solution at ?? ?????? is ?? ?? (?? ?? ?? )
= ?? . ???? ?? ???? ?????? -?? 
(A) ?????? . ???? ?? 
(B) ?????? ?? 
(C) ?????? . ?? ?? 
(D) ?????? . ???? ?? 
Ans: (D) A
2
 B
3
? 2 A
+
+ 3 B
-
 
?? = 0.6
n = 5
i = 1 + (n - 1)?? = 3.4
?T
b
= iKm
 = 3.4 × 0.52 × 1
 = 1.768 K
 T
b
= 373 + 1.768 = 374.768 K
 
Q2. The van't Hoff factor for a dilute aqueous solution of glucose is 
(A) Zero 
(B) 1.0 
(C) 1.5 
(D) 2.0 
Ans: (B) Since, glucose does not dissociate, ?? = 0 ? i = 1 
 
Q3. The correct relationship between the boiling points of very dilute solution of 
???????? ?? ( ?? ?? ?? ) and ???????? ?? (?? ?? ?? ) having the same molar concentration is 
(A) ?? ?? = ?? ?? 
(B) ?? ?? > ?? ?? 
(C) ?? ?? < ?? ?? 
(D) ?? ?? = ?? ?? 
Ans: (B) ??? ?? = ?? ?? ?? ?? 
For v equimolar solution are equimolal also very dilute. 
 ? ?T
b
? i
i
AlCl
3
> i
CaCl
2
( as i?? n
1
n
AlCl
3
= 4, n
CaCl
2
= 2)
?T
b
AlCl
3
> ?T
b
CaCl
2
 T
1
> T
2
 
Q4. A 0.001 molal solution of a complex [????
?? ] in water has the freezing point of 
-?? . ????????
°
?? . Assuming ?????? % ionization of the complex salt and ?? ?? for ?? ?? ?? = ?? . ???? 
????
-?? , what the correct representation for the complex 
Page 2


Solved Examples on Solutions 
JEE Mains 
Q1. 1.0 molal aqueous solution of an electrolyte ?? ?? ?? ?? is ???? % ionized. The boiling 
point of the solution at ?? ?????? is ?? ?? (?? ?? ?? )
= ?? . ???? ?? ???? ?????? -?? 
(A) ?????? . ???? ?? 
(B) ?????? ?? 
(C) ?????? . ?? ?? 
(D) ?????? . ???? ?? 
Ans: (D) A
2
 B
3
? 2 A
+
+ 3 B
-
 
?? = 0.6
n = 5
i = 1 + (n - 1)?? = 3.4
?T
b
= iKm
 = 3.4 × 0.52 × 1
 = 1.768 K
 T
b
= 373 + 1.768 = 374.768 K
 
Q2. The van't Hoff factor for a dilute aqueous solution of glucose is 
(A) Zero 
(B) 1.0 
(C) 1.5 
(D) 2.0 
Ans: (B) Since, glucose does not dissociate, ?? = 0 ? i = 1 
 
Q3. The correct relationship between the boiling points of very dilute solution of 
???????? ?? ( ?? ?? ?? ) and ???????? ?? (?? ?? ?? ) having the same molar concentration is 
(A) ?? ?? = ?? ?? 
(B) ?? ?? > ?? ?? 
(C) ?? ?? < ?? ?? 
(D) ?? ?? = ?? ?? 
Ans: (B) ??? ?? = ?? ?? ?? ?? 
For v equimolar solution are equimolal also very dilute. 
 ? ?T
b
? i
i
AlCl
3
> i
CaCl
2
( as i?? n
1
n
AlCl
3
= 4, n
CaCl
2
= 2)
?T
b
AlCl
3
> ?T
b
CaCl
2
 T
1
> T
2
 
Q4. A 0.001 molal solution of a complex [????
?? ] in water has the freezing point of 
-?? . ????????
°
?? . Assuming ?????? % ionization of the complex salt and ?? ?? for ?? ?? ?? = ?? . ???? 
????
-?? , what the correct representation for the complex 
(A) [????
?? ] 
(B) [????
?? ]?? 
(C) [????
?? ]?? ?? 
(D) [????
?? ]?? ?? 
Ans: (C) ??? ?? = ?? ?? ?? ?? 
i =
?T
f
K
f
m
=
0.0054
1.86 × 0.001
= 2.903
?? = 1
 ? 1 + (n - 1)?? = 2.9 ˜ 3
n - 1 = 2
n = 3
 
? Out of the given options, only (C) is possible 
 
Q5. The vapour pressure of a solution of a non-volatile electrolyte B in a solvent A 
is ???? % of the vapour pressure of the solvent at the same temperature. If the 
molecular weight of the solvent is 0.3 times the molecular weight of solute, the 
weight ratio of the solvent and solute are 
(A) 0.15 
(B) 5.7 
(C) 0.2 
(D) 4.0 
Ans: (B) We have 
?? = 0.95?? 0
?? 0
- ?? ?? 0
= ?? ?? = 0.05
?? ?? ?? ?? = 0.05
?? ?? ?? ?? +
?? ?? ?? ?? ?? ?? ?? ?? =
1
20
?? ?? ?? ?? +
1
20
?? ?? ?? ?? 19
20
?? ?? ?? ?? =
1
20
?? ?? ?? ?? ?? ?? ?? ?? = 19 ·
?? ?? ?? ?? 19 × 0.3 = 5.7
 
 
Q6.  The vapour pressure of a saturated solution of sparingly soluble salt (?????? ?? ) 
was ???? . ???? ???????? at ????
°
?? . If the vapour pressure of pure ?? ?? ?? is ???? . ???? ???????? at 
???? ?? , what is the solubility of sparingly soluble salt ?????? ?? in mole/litre 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
Page 3


Solved Examples on Solutions 
JEE Mains 
Q1. 1.0 molal aqueous solution of an electrolyte ?? ?? ?? ?? is ???? % ionized. The boiling 
point of the solution at ?? ?????? is ?? ?? (?? ?? ?? )
= ?? . ???? ?? ???? ?????? -?? 
(A) ?????? . ???? ?? 
(B) ?????? ?? 
(C) ?????? . ?? ?? 
(D) ?????? . ???? ?? 
Ans: (D) A
2
 B
3
? 2 A
+
+ 3 B
-
 
?? = 0.6
n = 5
i = 1 + (n - 1)?? = 3.4
?T
b
= iKm
 = 3.4 × 0.52 × 1
 = 1.768 K
 T
b
= 373 + 1.768 = 374.768 K
 
Q2. The van't Hoff factor for a dilute aqueous solution of glucose is 
(A) Zero 
(B) 1.0 
(C) 1.5 
(D) 2.0 
Ans: (B) Since, glucose does not dissociate, ?? = 0 ? i = 1 
 
Q3. The correct relationship between the boiling points of very dilute solution of 
???????? ?? ( ?? ?? ?? ) and ???????? ?? (?? ?? ?? ) having the same molar concentration is 
(A) ?? ?? = ?? ?? 
(B) ?? ?? > ?? ?? 
(C) ?? ?? < ?? ?? 
(D) ?? ?? = ?? ?? 
Ans: (B) ??? ?? = ?? ?? ?? ?? 
For v equimolar solution are equimolal also very dilute. 
 ? ?T
b
? i
i
AlCl
3
> i
CaCl
2
( as i?? n
1
n
AlCl
3
= 4, n
CaCl
2
= 2)
?T
b
AlCl
3
> ?T
b
CaCl
2
 T
1
> T
2
 
Q4. A 0.001 molal solution of a complex [????
?? ] in water has the freezing point of 
-?? . ????????
°
?? . Assuming ?????? % ionization of the complex salt and ?? ?? for ?? ?? ?? = ?? . ???? 
????
-?? , what the correct representation for the complex 
(A) [????
?? ] 
(B) [????
?? ]?? 
(C) [????
?? ]?? ?? 
(D) [????
?? ]?? ?? 
Ans: (C) ??? ?? = ?? ?? ?? ?? 
i =
?T
f
K
f
m
=
0.0054
1.86 × 0.001
= 2.903
?? = 1
 ? 1 + (n - 1)?? = 2.9 ˜ 3
n - 1 = 2
n = 3
 
? Out of the given options, only (C) is possible 
 
Q5. The vapour pressure of a solution of a non-volatile electrolyte B in a solvent A 
is ???? % of the vapour pressure of the solvent at the same temperature. If the 
molecular weight of the solvent is 0.3 times the molecular weight of solute, the 
weight ratio of the solvent and solute are 
(A) 0.15 
(B) 5.7 
(C) 0.2 
(D) 4.0 
Ans: (B) We have 
?? = 0.95?? 0
?? 0
- ?? ?? 0
= ?? ?? = 0.05
?? ?? ?? ?? = 0.05
?? ?? ?? ?? +
?? ?? ?? ?? ?? ?? ?? ?? =
1
20
?? ?? ?? ?? +
1
20
?? ?? ?? ?? 19
20
?? ?? ?? ?? =
1
20
?? ?? ?? ?? ?? ?? ?? ?? = 19 ·
?? ?? ?? ?? 19 × 0.3 = 5.7
 
 
Q6.  The vapour pressure of a saturated solution of sparingly soluble salt (?????? ?? ) 
was ???? . ???? ???????? at ????
°
?? . If the vapour pressure of pure ?? ?? ?? is ???? . ???? ???????? at 
???? ?? , what is the solubility of sparingly soluble salt ?????? ?? in mole/litre 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
(C) ?? . ???? × ????
-?? 
(D) ?? . ???? × ????
-?? 
Ans: (A) XCl
3
? X + 3Cl 
?? = 4
?? = 1
?? = 1 + 3 = 5
?? ?? =
?? 0
- ?? ?? 0
?? ?? =
17.25 - 17.2
17.25 × 4
?? ?? = 7.24 × 10
-4
=
?? ?? + ?? 
For n + N = 1, n = 7.24 × 10
-4
 
N = 0.999
 m
w
=
N · 18
1000
 V
w
=
N · 18
1000
 L
 ? [A] =
n
V
w
X
A
· 1000
(1 - X
A
) · 18
[ A] = 4.04 × 10
-2
 mole/L
 
Q7. At 300K, the vapour pressure of an ideal solution containing 3 mole of A and 2 
mole of B is 600 torr. At the same temperature, if 1.5 mole of ?? and 0.5 mole of ?? 
(non-volatile) are added to this solution the vapour pressure of solution increases 
by 30 torr. What is the value of ?? ?? 
?? ? 
(A) 940 
(B) 405 
(C) 90 
(D) None of these 
Ans: (C) Initially 
P = P
A
+ P
B
= P
A
0
· X
A
+ P
B
0
X
B
 
600 =
3
5
?? ?? 0
+
2
5
?? ?? 0
3?? ?? 0
+ 2?? ?? 0
= 3000
9?? ?? 0
+ 6?? ?? 0
= 9000… (i)
 
After adding C,  
Page 4


Solved Examples on Solutions 
JEE Mains 
Q1. 1.0 molal aqueous solution of an electrolyte ?? ?? ?? ?? is ???? % ionized. The boiling 
point of the solution at ?? ?????? is ?? ?? (?? ?? ?? )
= ?? . ???? ?? ???? ?????? -?? 
(A) ?????? . ???? ?? 
(B) ?????? ?? 
(C) ?????? . ?? ?? 
(D) ?????? . ???? ?? 
Ans: (D) A
2
 B
3
? 2 A
+
+ 3 B
-
 
?? = 0.6
n = 5
i = 1 + (n - 1)?? = 3.4
?T
b
= iKm
 = 3.4 × 0.52 × 1
 = 1.768 K
 T
b
= 373 + 1.768 = 374.768 K
 
Q2. The van't Hoff factor for a dilute aqueous solution of glucose is 
(A) Zero 
(B) 1.0 
(C) 1.5 
(D) 2.0 
Ans: (B) Since, glucose does not dissociate, ?? = 0 ? i = 1 
 
Q3. The correct relationship between the boiling points of very dilute solution of 
???????? ?? ( ?? ?? ?? ) and ???????? ?? (?? ?? ?? ) having the same molar concentration is 
(A) ?? ?? = ?? ?? 
(B) ?? ?? > ?? ?? 
(C) ?? ?? < ?? ?? 
(D) ?? ?? = ?? ?? 
Ans: (B) ??? ?? = ?? ?? ?? ?? 
For v equimolar solution are equimolal also very dilute. 
 ? ?T
b
? i
i
AlCl
3
> i
CaCl
2
( as i?? n
1
n
AlCl
3
= 4, n
CaCl
2
= 2)
?T
b
AlCl
3
> ?T
b
CaCl
2
 T
1
> T
2
 
Q4. A 0.001 molal solution of a complex [????
?? ] in water has the freezing point of 
-?? . ????????
°
?? . Assuming ?????? % ionization of the complex salt and ?? ?? for ?? ?? ?? = ?? . ???? 
????
-?? , what the correct representation for the complex 
(A) [????
?? ] 
(B) [????
?? ]?? 
(C) [????
?? ]?? ?? 
(D) [????
?? ]?? ?? 
Ans: (C) ??? ?? = ?? ?? ?? ?? 
i =
?T
f
K
f
m
=
0.0054
1.86 × 0.001
= 2.903
?? = 1
 ? 1 + (n - 1)?? = 2.9 ˜ 3
n - 1 = 2
n = 3
 
? Out of the given options, only (C) is possible 
 
Q5. The vapour pressure of a solution of a non-volatile electrolyte B in a solvent A 
is ???? % of the vapour pressure of the solvent at the same temperature. If the 
molecular weight of the solvent is 0.3 times the molecular weight of solute, the 
weight ratio of the solvent and solute are 
(A) 0.15 
(B) 5.7 
(C) 0.2 
(D) 4.0 
Ans: (B) We have 
?? = 0.95?? 0
?? 0
- ?? ?? 0
= ?? ?? = 0.05
?? ?? ?? ?? = 0.05
?? ?? ?? ?? +
?? ?? ?? ?? ?? ?? ?? ?? =
1
20
?? ?? ?? ?? +
1
20
?? ?? ?? ?? 19
20
?? ?? ?? ?? =
1
20
?? ?? ?? ?? ?? ?? ?? ?? = 19 ·
?? ?? ?? ?? 19 × 0.3 = 5.7
 
 
Q6.  The vapour pressure of a saturated solution of sparingly soluble salt (?????? ?? ) 
was ???? . ???? ???????? at ????
°
?? . If the vapour pressure of pure ?? ?? ?? is ???? . ???? ???????? at 
???? ?? , what is the solubility of sparingly soluble salt ?????? ?? in mole/litre 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
(C) ?? . ???? × ????
-?? 
(D) ?? . ???? × ????
-?? 
Ans: (A) XCl
3
? X + 3Cl 
?? = 4
?? = 1
?? = 1 + 3 = 5
?? ?? =
?? 0
- ?? ?? 0
?? ?? =
17.25 - 17.2
17.25 × 4
?? ?? = 7.24 × 10
-4
=
?? ?? + ?? 
For n + N = 1, n = 7.24 × 10
-4
 
N = 0.999
 m
w
=
N · 18
1000
 V
w
=
N · 18
1000
 L
 ? [A] =
n
V
w
X
A
· 1000
(1 - X
A
) · 18
[ A] = 4.04 × 10
-2
 mole/L
 
Q7. At 300K, the vapour pressure of an ideal solution containing 3 mole of A and 2 
mole of B is 600 torr. At the same temperature, if 1.5 mole of ?? and 0.5 mole of ?? 
(non-volatile) are added to this solution the vapour pressure of solution increases 
by 30 torr. What is the value of ?? ?? 
?? ? 
(A) 940 
(B) 405 
(C) 90 
(D) None of these 
Ans: (C) Initially 
P = P
A
+ P
B
= P
A
0
· X
A
+ P
B
0
X
B
 
600 =
3
5
?? ?? 0
+
2
5
?? ?? 0
3?? ?? 0
+ 2?? ?? 0
= 3000
9?? ?? 0
+ 6?? ?? 0
= 9000… (i)
 
After adding C,  
?? = ?? ?? + ?? ?? 630 =
3 + 1.5
3 + 2 + 1.5 + 0.5
?? ?? 0
+
2
3 + 2 + 1.5 + 0.5
?? ?? 0
630 =
9
14
?? ?? 0
+
4
14
?? ?? 0
9?? ?? 
0
+ 4?? ?? 0
= 8820… (ii)
 
(i)- (ii) ? 2P
B
 
0
= 180 
?? ?? 0
= 90 torr  
 
Q8. The freezing point depression of a ?? . ???? aq. solution of weak acid (???? ) is 
-?? . ????
°
?? . What is the value of equilibrium constant for the reaction? 
???? (???? )?? ?? +
(???? ) + ?? -
(???? ) [Given: ?? ?? for water = ?? . ?? ???? ?????? -?? ?? and Molality = 
Molarity ] 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
(C) ?? . ???? × ????
-?? 
(D) ?? . ???? × ????
-?? 
Ans: (B) HX ? H
+
+ X
-
 
?? = 2
?? = 1 + (?? - 1)?? = 1 + ?? ?? = ?? = 0.1
??? ?? = ?? ?? ?? ?? ?? =
??? ?? ?? ?? ?? =
0.2
1.8 × 0.1
= 1.11
?? = 0.11
 ? ?? ?? =
?? ?? 2
1 - ?? =
0.1 × (0.11)
2
(1 - 0.11)
= 1.35 × 10
-3
 
Q9. Equimolar solutions in the same solvent have 
(A) Same boiling point but different freezing point 
(B) Same freezing point but different boiling point 
(C) Same boiling and same freezing point 
(D) Different boiling and different freezing point 
Ans: (C) Equimolar solutions in the same solvent have same boiling and same freezing 
point. 
 
Q10. Two liquids ?? and ?? form an ideal solution. At ???? ?? , vapour pressure of the 
solution containing 1 mol of ?? and 3 moles of ?? is ?? ???? ???????? . At the same 
temperature, if ?? ?????? of ?? is further added to this solution, vapour pressure of the 
solution increases by ?? ???????? . Vapour pressure (in ???????? ) of ?? and ?? in their 
pure states will be respectively 
(A) 200 and 300 
Page 5


Solved Examples on Solutions 
JEE Mains 
Q1. 1.0 molal aqueous solution of an electrolyte ?? ?? ?? ?? is ???? % ionized. The boiling 
point of the solution at ?? ?????? is ?? ?? (?? ?? ?? )
= ?? . ???? ?? ???? ?????? -?? 
(A) ?????? . ???? ?? 
(B) ?????? ?? 
(C) ?????? . ?? ?? 
(D) ?????? . ???? ?? 
Ans: (D) A
2
 B
3
? 2 A
+
+ 3 B
-
 
?? = 0.6
n = 5
i = 1 + (n - 1)?? = 3.4
?T
b
= iKm
 = 3.4 × 0.52 × 1
 = 1.768 K
 T
b
= 373 + 1.768 = 374.768 K
 
Q2. The van't Hoff factor for a dilute aqueous solution of glucose is 
(A) Zero 
(B) 1.0 
(C) 1.5 
(D) 2.0 
Ans: (B) Since, glucose does not dissociate, ?? = 0 ? i = 1 
 
Q3. The correct relationship between the boiling points of very dilute solution of 
???????? ?? ( ?? ?? ?? ) and ???????? ?? (?? ?? ?? ) having the same molar concentration is 
(A) ?? ?? = ?? ?? 
(B) ?? ?? > ?? ?? 
(C) ?? ?? < ?? ?? 
(D) ?? ?? = ?? ?? 
Ans: (B) ??? ?? = ?? ?? ?? ?? 
For v equimolar solution are equimolal also very dilute. 
 ? ?T
b
? i
i
AlCl
3
> i
CaCl
2
( as i?? n
1
n
AlCl
3
= 4, n
CaCl
2
= 2)
?T
b
AlCl
3
> ?T
b
CaCl
2
 T
1
> T
2
 
Q4. A 0.001 molal solution of a complex [????
?? ] in water has the freezing point of 
-?? . ????????
°
?? . Assuming ?????? % ionization of the complex salt and ?? ?? for ?? ?? ?? = ?? . ???? 
????
-?? , what the correct representation for the complex 
(A) [????
?? ] 
(B) [????
?? ]?? 
(C) [????
?? ]?? ?? 
(D) [????
?? ]?? ?? 
Ans: (C) ??? ?? = ?? ?? ?? ?? 
i =
?T
f
K
f
m
=
0.0054
1.86 × 0.001
= 2.903
?? = 1
 ? 1 + (n - 1)?? = 2.9 ˜ 3
n - 1 = 2
n = 3
 
? Out of the given options, only (C) is possible 
 
Q5. The vapour pressure of a solution of a non-volatile electrolyte B in a solvent A 
is ???? % of the vapour pressure of the solvent at the same temperature. If the 
molecular weight of the solvent is 0.3 times the molecular weight of solute, the 
weight ratio of the solvent and solute are 
(A) 0.15 
(B) 5.7 
(C) 0.2 
(D) 4.0 
Ans: (B) We have 
?? = 0.95?? 0
?? 0
- ?? ?? 0
= ?? ?? = 0.05
?? ?? ?? ?? = 0.05
?? ?? ?? ?? +
?? ?? ?? ?? ?? ?? ?? ?? =
1
20
?? ?? ?? ?? +
1
20
?? ?? ?? ?? 19
20
?? ?? ?? ?? =
1
20
?? ?? ?? ?? ?? ?? ?? ?? = 19 ·
?? ?? ?? ?? 19 × 0.3 = 5.7
 
 
Q6.  The vapour pressure of a saturated solution of sparingly soluble salt (?????? ?? ) 
was ???? . ???? ???????? at ????
°
?? . If the vapour pressure of pure ?? ?? ?? is ???? . ???? ???????? at 
???? ?? , what is the solubility of sparingly soluble salt ?????? ?? in mole/litre 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
(C) ?? . ???? × ????
-?? 
(D) ?? . ???? × ????
-?? 
Ans: (A) XCl
3
? X + 3Cl 
?? = 4
?? = 1
?? = 1 + 3 = 5
?? ?? =
?? 0
- ?? ?? 0
?? ?? =
17.25 - 17.2
17.25 × 4
?? ?? = 7.24 × 10
-4
=
?? ?? + ?? 
For n + N = 1, n = 7.24 × 10
-4
 
N = 0.999
 m
w
=
N · 18
1000
 V
w
=
N · 18
1000
 L
 ? [A] =
n
V
w
X
A
· 1000
(1 - X
A
) · 18
[ A] = 4.04 × 10
-2
 mole/L
 
Q7. At 300K, the vapour pressure of an ideal solution containing 3 mole of A and 2 
mole of B is 600 torr. At the same temperature, if 1.5 mole of ?? and 0.5 mole of ?? 
(non-volatile) are added to this solution the vapour pressure of solution increases 
by 30 torr. What is the value of ?? ?? 
?? ? 
(A) 940 
(B) 405 
(C) 90 
(D) None of these 
Ans: (C) Initially 
P = P
A
+ P
B
= P
A
0
· X
A
+ P
B
0
X
B
 
600 =
3
5
?? ?? 0
+
2
5
?? ?? 0
3?? ?? 0
+ 2?? ?? 0
= 3000
9?? ?? 0
+ 6?? ?? 0
= 9000… (i)
 
After adding C,  
?? = ?? ?? + ?? ?? 630 =
3 + 1.5
3 + 2 + 1.5 + 0.5
?? ?? 0
+
2
3 + 2 + 1.5 + 0.5
?? ?? 0
630 =
9
14
?? ?? 0
+
4
14
?? ?? 0
9?? ?? 
0
+ 4?? ?? 0
= 8820… (ii)
 
(i)- (ii) ? 2P
B
 
0
= 180 
?? ?? 0
= 90 torr  
 
Q8. The freezing point depression of a ?? . ???? aq. solution of weak acid (???? ) is 
-?? . ????
°
?? . What is the value of equilibrium constant for the reaction? 
???? (???? )?? ?? +
(???? ) + ?? -
(???? ) [Given: ?? ?? for water = ?? . ?? ???? ?????? -?? ?? and Molality = 
Molarity ] 
(A) ?? . ???? × ????
-?? 
(B) ?? . ???? × ????
-?? 
(C) ?? . ???? × ????
-?? 
(D) ?? . ???? × ????
-?? 
Ans: (B) HX ? H
+
+ X
-
 
?? = 2
?? = 1 + (?? - 1)?? = 1 + ?? ?? = ?? = 0.1
??? ?? = ?? ?? ?? ?? ?? =
??? ?? ?? ?? ?? =
0.2
1.8 × 0.1
= 1.11
?? = 0.11
 ? ?? ?? =
?? ?? 2
1 - ?? =
0.1 × (0.11)
2
(1 - 0.11)
= 1.35 × 10
-3
 
Q9. Equimolar solutions in the same solvent have 
(A) Same boiling point but different freezing point 
(B) Same freezing point but different boiling point 
(C) Same boiling and same freezing point 
(D) Different boiling and different freezing point 
Ans: (C) Equimolar solutions in the same solvent have same boiling and same freezing 
point. 
 
Q10. Two liquids ?? and ?? form an ideal solution. At ???? ?? , vapour pressure of the 
solution containing 1 mol of ?? and 3 moles of ?? is ?? ???? ???????? . At the same 
temperature, if ?? ?????? of ?? is further added to this solution, vapour pressure of the 
solution increases by ?? ???????? . Vapour pressure (in ???????? ) of ?? and ?? in their 
pure states will be respectively 
(A) 200 and 300 
(B) 300 and 400 
(C) 400 and 600 
(D) 500 and 600 
Ans: (C) As ?? T
= P
x
0
· X
x
+ P
y
0
· X
y
 
550 = ?? ?? 0
·
1
4
+ ?? ?? 0
·
3
4
?? ?? 0
+ 3?? ?? 0
= 2200
 
On adding 1 mole of ?? (?? ) be comes 560 so 
560 = ?? ?? 0
·
1
5
+ ?? ?? 0
·
4
5
?? ?? 0
+ 4?? ?? 0
= 2800
 
From eq. (i) and (ii)  
?? ?? 0
= 400 mmHg
?? ?? 0
= 600 mmHg
 
 
Q11. The vapour pressure of water at ????
°
?? is ???? . ?? ???? ???? . If ???? ?? of glucose 
(?? ?? ?? ????
?? ?? ) is added to ?????? . ?? ?? of water at ????
°
?? the vapour pressure of the resulting 
solution will be 
(A) ???? . ?????? ???????? 
(B) ???? . ?????? ???????? 
(C) ???? . ?????? ???????? 
(D) ???? . ?????? ???????? 
Ans: (C) 
?? 0
-?? ?? ?? 0
=
?? ?? +?? 
n =
18
180
= 0.1 N =
178.2
18
= 9.9 = 0.1 N
175 - P
0
17.5
=
0.1
0.1 + 9.9
;
175 - P
0
17.5
=
1
100
1750 - 100P
s
= 17.5; 1732.5 = 100p
s
P
s
= 17.325 mmHg
 
Q12. A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 
?????? ???? at ???? ?? . The vapour pressure of propyl alcohol is ???? ???? . If the mole 
fraction of ethyl alcohol is 0.6, its vapour pressure (in ?? ) at the same temperature 
will be 
(A) 350 
(B) 300 
(C) 700 
(D) 360 
Ans: (A) Let the vapour pressue of pure ethyl alcohol be P, 
According to Raoult's law