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Page 1
CBSE XI | Chemistry
Sample Paper – 3 Solution
CBSE
Class XI Chemistry
Sample Paper – 3 Solution
Section A
1. HI>HBr>HCl>HF
2. BeCl2: Linear
SiCl4: Tetrahedral
OR
The electron pairs involved in the bond formation are known as bond pairs or shared
pairs.
3. IUPAC name of allyl alcohol: Prop-2-en-1-ol
4. The amount of oxygen required by bacteria to breakdown the organic matter present in
a certain volume of a sample of water is called biochemical oxygen demand.
OR
Carboxyhaemolobin is the compound formed when CO combines with blood.
5. Sodium (Na) – Yellow
Poassium (K) - Violet
Section B
6. Metallic character decreases and non metallic character increases in moving from left to
right in a period. This is due to increase in ionization enthalpy and electron gain
enthalpy.
7. Increasing order of size: Al
3+
< Mg
2+
< Na
+
< F
-
< O
2-
This is an isoelectronic series i.e. the number electrons are the same in all the elements.
Thus, as the effective nuclear charge decreases, electrons are held away from the
nucleus and thus size increases.
8. Given:
Velocity of electron = 2.07×10
7
m/s
Mass of electron = 9.1×10
-31
kg
We know,
Page 2
CBSE XI | Chemistry
Sample Paper – 3 Solution
CBSE
Class XI Chemistry
Sample Paper – 3 Solution
Section A
1. HI>HBr>HCl>HF
2. BeCl2: Linear
SiCl4: Tetrahedral
OR
The electron pairs involved in the bond formation are known as bond pairs or shared
pairs.
3. IUPAC name of allyl alcohol: Prop-2-en-1-ol
4. The amount of oxygen required by bacteria to breakdown the organic matter present in
a certain volume of a sample of water is called biochemical oxygen demand.
OR
Carboxyhaemolobin is the compound formed when CO combines with blood.
5. Sodium (Na) – Yellow
Poassium (K) - Violet
Section B
6. Metallic character decreases and non metallic character increases in moving from left to
right in a period. This is due to increase in ionization enthalpy and electron gain
enthalpy.
7. Increasing order of size: Al
3+
< Mg
2+
< Na
+
< F
-
< O
2-
This is an isoelectronic series i.e. the number electrons are the same in all the elements.
Thus, as the effective nuclear charge decreases, electrons are held away from the
nucleus and thus size increases.
8. Given:
Velocity of electron = 2.07×10
7
m/s
Mass of electron = 9.1×10
-31
kg
We know,
CBSE XI | Chemistry
Sample Paper – 3 Solution
34
31 7
11
h
mv
6.63 10
9.1 10 2.05 0.5 10
3.55 10 m
?
?
?
??
?
?
? ? ? ?
??
9. Given:
Pressure P = 5 bar
Molar mass of nitrogen M = 28 g/mol
Density of nitrogen,
? ?
PM
RT
Density of gaseousoxideis,
0.987 5 x
0.987 5 28
273 0.0821 273 0.0821
0.987 5 28 273 0.0821
X
273 0.0821 0..987 5
70
??
??
??
?
??
? ? ? ?
?
? ? ?
?
The molar mass of the oxide is 70 g/mol
10. 2H2O+ 2 F2 ? 4HF+ O2
In this reaction H2O is getting oxidized to O2 and F2 is getting reduced to F
-
ion.
Therefore, F2 is the oxidizing agent and H2O is reducing agent.
OR
(a) PbS(g) + H2O2(aq) ? PbSO 4(s) + 4H2O(l)
(b) CO(g) + 2 H2(g)
Cobalt
catalyst
? ? ? ? CH 3OH
11. Given:
No. Nuclei No. of protons No. of neutrons
1
56
26
Fe 26 30
2
88
38
Sr 38 50
Page 3
CBSE XI | Chemistry
Sample Paper – 3 Solution
CBSE
Class XI Chemistry
Sample Paper – 3 Solution
Section A
1. HI>HBr>HCl>HF
2. BeCl2: Linear
SiCl4: Tetrahedral
OR
The electron pairs involved in the bond formation are known as bond pairs or shared
pairs.
3. IUPAC name of allyl alcohol: Prop-2-en-1-ol
4. The amount of oxygen required by bacteria to breakdown the organic matter present in
a certain volume of a sample of water is called biochemical oxygen demand.
OR
Carboxyhaemolobin is the compound formed when CO combines with blood.
5. Sodium (Na) – Yellow
Poassium (K) - Violet
Section B
6. Metallic character decreases and non metallic character increases in moving from left to
right in a period. This is due to increase in ionization enthalpy and electron gain
enthalpy.
7. Increasing order of size: Al
3+
< Mg
2+
< Na
+
< F
-
< O
2-
This is an isoelectronic series i.e. the number electrons are the same in all the elements.
Thus, as the effective nuclear charge decreases, electrons are held away from the
nucleus and thus size increases.
8. Given:
Velocity of electron = 2.07×10
7
m/s
Mass of electron = 9.1×10
-31
kg
We know,
CBSE XI | Chemistry
Sample Paper – 3 Solution
34
31 7
11
h
mv
6.63 10
9.1 10 2.05 0.5 10
3.55 10 m
?
?
?
??
?
?
? ? ? ?
??
9. Given:
Pressure P = 5 bar
Molar mass of nitrogen M = 28 g/mol
Density of nitrogen,
? ?
PM
RT
Density of gaseousoxideis,
0.987 5 x
0.987 5 28
273 0.0821 273 0.0821
0.987 5 28 273 0.0821
X
273 0.0821 0..987 5
70
??
??
??
?
??
? ? ? ?
?
? ? ?
?
The molar mass of the oxide is 70 g/mol
10. 2H2O+ 2 F2 ? 4HF+ O2
In this reaction H2O is getting oxidized to O2 and F2 is getting reduced to F
-
ion.
Therefore, F2 is the oxidizing agent and H2O is reducing agent.
OR
(a) PbS(g) + H2O2(aq) ? PbSO 4(s) + 4H2O(l)
(b) CO(g) + 2 H2(g)
Cobalt
catalyst
? ? ? ? CH 3OH
11. Given:
No. Nuclei No. of protons No. of neutrons
1
56
26
Fe 26 30
2
88
38
Sr 38 50
CBSE XI | Chemistry
Sample Paper – 3 Solution
12. Molar mass of methanol (CH3OH) = 32 g/mol
= 0.032 kg/mol
Molarity of solution =
0.793
0.032
24.78mol / l
?
?
We have,
M1V1 = M2V2
24.78 × V1 = 0.25 × 2.5
V1 = 25.22 ml
The required volume is 25.22 ml
OR
Given:
M= 3 mol/lit
Mass of NaCl in 1 litre solution = 3×58.5
= 175.5 g
Mass of water in solution = 1000 × 1.25
= 1250 g
Mass of water in solution = 1250- 175.5
= 1074.5 g
Molarity
Number of moles of solute
Massof solvent in kg
3
1.074
2.79m
?
?
?
Page 4
CBSE XI | Chemistry
Sample Paper – 3 Solution
CBSE
Class XI Chemistry
Sample Paper – 3 Solution
Section A
1. HI>HBr>HCl>HF
2. BeCl2: Linear
SiCl4: Tetrahedral
OR
The electron pairs involved in the bond formation are known as bond pairs or shared
pairs.
3. IUPAC name of allyl alcohol: Prop-2-en-1-ol
4. The amount of oxygen required by bacteria to breakdown the organic matter present in
a certain volume of a sample of water is called biochemical oxygen demand.
OR
Carboxyhaemolobin is the compound formed when CO combines with blood.
5. Sodium (Na) – Yellow
Poassium (K) - Violet
Section B
6. Metallic character decreases and non metallic character increases in moving from left to
right in a period. This is due to increase in ionization enthalpy and electron gain
enthalpy.
7. Increasing order of size: Al
3+
< Mg
2+
< Na
+
< F
-
< O
2-
This is an isoelectronic series i.e. the number electrons are the same in all the elements.
Thus, as the effective nuclear charge decreases, electrons are held away from the
nucleus and thus size increases.
8. Given:
Velocity of electron = 2.07×10
7
m/s
Mass of electron = 9.1×10
-31
kg
We know,
CBSE XI | Chemistry
Sample Paper – 3 Solution
34
31 7
11
h
mv
6.63 10
9.1 10 2.05 0.5 10
3.55 10 m
?
?
?
??
?
?
? ? ? ?
??
9. Given:
Pressure P = 5 bar
Molar mass of nitrogen M = 28 g/mol
Density of nitrogen,
? ?
PM
RT
Density of gaseousoxideis,
0.987 5 x
0.987 5 28
273 0.0821 273 0.0821
0.987 5 28 273 0.0821
X
273 0.0821 0..987 5
70
??
??
??
?
??
? ? ? ?
?
? ? ?
?
The molar mass of the oxide is 70 g/mol
10. 2H2O+ 2 F2 ? 4HF+ O2
In this reaction H2O is getting oxidized to O2 and F2 is getting reduced to F
-
ion.
Therefore, F2 is the oxidizing agent and H2O is reducing agent.
OR
(a) PbS(g) + H2O2(aq) ? PbSO 4(s) + 4H2O(l)
(b) CO(g) + 2 H2(g)
Cobalt
catalyst
? ? ? ? CH 3OH
11. Given:
No. Nuclei No. of protons No. of neutrons
1
56
26
Fe 26 30
2
88
38
Sr 38 50
CBSE XI | Chemistry
Sample Paper – 3 Solution
12. Molar mass of methanol (CH3OH) = 32 g/mol
= 0.032 kg/mol
Molarity of solution =
0.793
0.032
24.78mol / l
?
?
We have,
M1V1 = M2V2
24.78 × V1 = 0.25 × 2.5
V1 = 25.22 ml
The required volume is 25.22 ml
OR
Given:
M= 3 mol/lit
Mass of NaCl in 1 litre solution = 3×58.5
= 175.5 g
Mass of water in solution = 1000 × 1.25
= 1250 g
Mass of water in solution = 1250- 175.5
= 1074.5 g
Molarity
Number of moles of solute
Massof solvent in kg
3
1.074
2.79m
?
?
?
CBSE XI | Chemistry
Sample Paper – 3 Solution
Section C
13.
We know,
? ?
? ?
? ?
? ?
18 2
n 2
18 2
1 2
18
2
n
2
n
2.18 10 Z
E
n
For He ,
n 1, n 2
2.18 10 2
E
1
8.72 10 J
0.0529 n
r
Z
Here,n 1, Z 2
0.0529 1
r
2
0.02645nm
?
?
?
?
??
?
??
??
?
? ? ?
?
??
?
?
Energy is 8.72 ×10
-18
J
Radius of the orbit is 0.02645 nm
OR
Let us find out the atomic number of element.
Let the number of protons = x
? ?
x 31.7
Number of neutrons x
100
x 0.317x
Massno.of element No.of protons No.of neutrons
81 x x 0.317x
81 2.317x
x 35
No.of protons 35
No. of neutrons 81 35
46
Atomic numer of element is 35
?
??
??
??
? ? ?
?
?
??
??
?
The element with atomic number 35 is bromine (Br).
Page 5
CBSE XI | Chemistry
Sample Paper – 3 Solution
CBSE
Class XI Chemistry
Sample Paper – 3 Solution
Section A
1. HI>HBr>HCl>HF
2. BeCl2: Linear
SiCl4: Tetrahedral
OR
The electron pairs involved in the bond formation are known as bond pairs or shared
pairs.
3. IUPAC name of allyl alcohol: Prop-2-en-1-ol
4. The amount of oxygen required by bacteria to breakdown the organic matter present in
a certain volume of a sample of water is called biochemical oxygen demand.
OR
Carboxyhaemolobin is the compound formed when CO combines with blood.
5. Sodium (Na) – Yellow
Poassium (K) - Violet
Section B
6. Metallic character decreases and non metallic character increases in moving from left to
right in a period. This is due to increase in ionization enthalpy and electron gain
enthalpy.
7. Increasing order of size: Al
3+
< Mg
2+
< Na
+
< F
-
< O
2-
This is an isoelectronic series i.e. the number electrons are the same in all the elements.
Thus, as the effective nuclear charge decreases, electrons are held away from the
nucleus and thus size increases.
8. Given:
Velocity of electron = 2.07×10
7
m/s
Mass of electron = 9.1×10
-31
kg
We know,
CBSE XI | Chemistry
Sample Paper – 3 Solution
34
31 7
11
h
mv
6.63 10
9.1 10 2.05 0.5 10
3.55 10 m
?
?
?
??
?
?
? ? ? ?
??
9. Given:
Pressure P = 5 bar
Molar mass of nitrogen M = 28 g/mol
Density of nitrogen,
? ?
PM
RT
Density of gaseousoxideis,
0.987 5 x
0.987 5 28
273 0.0821 273 0.0821
0.987 5 28 273 0.0821
X
273 0.0821 0..987 5
70
??
??
??
?
??
? ? ? ?
?
? ? ?
?
The molar mass of the oxide is 70 g/mol
10. 2H2O+ 2 F2 ? 4HF+ O2
In this reaction H2O is getting oxidized to O2 and F2 is getting reduced to F
-
ion.
Therefore, F2 is the oxidizing agent and H2O is reducing agent.
OR
(a) PbS(g) + H2O2(aq) ? PbSO 4(s) + 4H2O(l)
(b) CO(g) + 2 H2(g)
Cobalt
catalyst
? ? ? ? CH 3OH
11. Given:
No. Nuclei No. of protons No. of neutrons
1
56
26
Fe 26 30
2
88
38
Sr 38 50
CBSE XI | Chemistry
Sample Paper – 3 Solution
12. Molar mass of methanol (CH3OH) = 32 g/mol
= 0.032 kg/mol
Molarity of solution =
0.793
0.032
24.78mol / l
?
?
We have,
M1V1 = M2V2
24.78 × V1 = 0.25 × 2.5
V1 = 25.22 ml
The required volume is 25.22 ml
OR
Given:
M= 3 mol/lit
Mass of NaCl in 1 litre solution = 3×58.5
= 175.5 g
Mass of water in solution = 1000 × 1.25
= 1250 g
Mass of water in solution = 1250- 175.5
= 1074.5 g
Molarity
Number of moles of solute
Massof solvent in kg
3
1.074
2.79m
?
?
?
CBSE XI | Chemistry
Sample Paper – 3 Solution
Section C
13.
We know,
? ?
? ?
? ?
? ?
18 2
n 2
18 2
1 2
18
2
n
2
n
2.18 10 Z
E
n
For He ,
n 1, n 2
2.18 10 2
E
1
8.72 10 J
0.0529 n
r
Z
Here,n 1, Z 2
0.0529 1
r
2
0.02645nm
?
?
?
?
??
?
??
??
?
? ? ?
?
??
?
?
Energy is 8.72 ×10
-18
J
Radius of the orbit is 0.02645 nm
OR
Let us find out the atomic number of element.
Let the number of protons = x
? ?
x 31.7
Number of neutrons x
100
x 0.317x
Massno.of element No.of protons No.of neutrons
81 x x 0.317x
81 2.317x
x 35
No.of protons 35
No. of neutrons 81 35
46
Atomic numer of element is 35
?
??
??
??
? ? ?
?
?
??
??
?
The element with atomic number 35 is bromine (Br).
CBSE XI | Chemistry
Sample Paper – 3 Solution
14. The balanced chemical equation is
22
2CO O 2CO
2mol 1mol
2x22.4L 22.4L
? ? ? ?
Volume of oxygen required to convert 2 x 22.4 L of CO at N.T.P. = 22.4 L
Volume of oxygen required to convert 5.2 L of CO at N.T.P. = xL
x
22.4
5.2 2.6
2 22.4
?
OR
(i) H2
+
is more stable than H2
-
as it contains no electron in antibonding MO while latter
contains an electron in antibonding MO making it less st
(ii) PCl5 contains axial and equatorial bonds. Axial bonds are longer than equatorial
bonds as they face more repulsion from equatorial bonds. Hence axial bonds are
weaker than equatorial bonds.
(iii) NaI is more covalent due to high polarizability of iodide ion due to its bigger size
than chloride ion.
15.
(i) This is due to the reason that the molecules which undergo evaporation are high
energy molecules and therefore, the kinetic energy of the remaining molecules
becomes less. Since the remaining molecules have lower average kinetic energy,
their temperature becomes low.
(ii) This is due to surface tension of liquids. Due to surface tension, the molecules of a
liquid, try to make surface area to be minimum and for a given volume, sphere has
the minimum surface area. Therefore the falling liquid drops are spherical.
(iii) Intermolecular forces are stronger in acetone than in ether. Thus the vapour
pressure of acetone is less than ether.
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