JEE Chemistry Hydrogen MCQs Set 13

Answer: (c) molecular state

Explanation:
1. At ordinary temperature hydrogen exists as diatomic \( \ce{H2} \) molecules.
2. Each molecule has a complete duplet and a strong H–H bond (bond enthalpy about 436 kJ/mol), so it is stable and sluggish.
3. Only at very high temperature does it dissociate into reactive atoms.

Teacher's Note:
1. R
2. e
3. a
4. c
5. t
6. i
7. v
8. i
9. t
10. y
11.
12. o
13. f
14.
15. h
16. y
17. d
18. r
19. o
20. g
21. e
22. n
23.
24. d
25. e
26. p
27. e
28. n
29. d
30. s
31.
32. o
33. n
34.
35. t
36. h
37. e
38.
39. s
40. t
41. r
42. o
43. n
44. g
45.
46. H
47. –
48. H
49.
50. b
51. o
52. n
53. d
54. ,
55.
56. n
57. o
58. t
59.
60. o
61. n
62.
63. t
64. h
65. e
66.
67. p
68. h
69. y
70. s
71. i
72. c
73. a
74. l
75.
76. s
77. t
78. a
79. t
80. e
81. .
82.
83. A
84. t
85. o
86. m
87. i
88. c
89.
90. h
91. y
92. d
93. r
94. o
95. g
96. e
97. n
98. ,
99.
100. w
101. i
102. t
103. h
104.
105. a
106. n
107.
108. i
109. n
110. c
111. o
112. m
113. p
114. l
115. e
116. t
117. e
118.
119. d
120. u
121. p
122. l
123. e
124. t
125. ,
126.
127. i
128. s
129.
130. t
131. h
132. e
133.
134. h
135. i
136. g
137. h
138. l
139. y
140.
141. r
142. e
143. a
144. c
145. t
146. i
147. v
148. e
149.
150. f
151. o
152. r
153. m
154. .

Answer: (d) small size

Explanation:
1. Hydrogen has a single electron in the 1s orbital, very close to the nucleus.
2. Its atomic size is very small, so the nucleus holds the electron firmly.
3. Alkali metals are much larger, so their outer electron is lost easily.

Teacher's Note:
1. I
2. o
3. n
4. i
5. s
6. a
7. t
8. i
9. o
10. n
11.
12. e
13. n
14. e
15. r
16. g
17. y
18.
19. d
20. e
21. c
22. r
23. e
24. a
25. s
26. e
27. s
28.
29. a
30. s
31.
32. a
33. t
34. o
35. m
36. i
37. c
38.
39. s
40. i
41. z
42. e
43.
44. i
45. n
46. c
47. r
48. e
49. a
50. s
51. e
52. s
53. .
54.
55. H
56. y
57. d
58. r
59. o
60. g
61. e
62. n
63.
64. (
65. 1
66. 3
67. 1
68. 2
69.
70. k
71. J
72. /
73. m
74. o
75. l
76. )
77.
78. i
79. s
80.
81. f
82. a
83. r
84.
85. a
86. b
87. o
88. v
89. e
90.
91. l
92. i
93. t
94. h
95. i
96. u
97. m
98.
99. (
100. 5
101. 2
102. 0
103.
104. k
105. J
106. /
107. m
108. o
109. l
110. )
111. .

Answer: (c) It cannot be placed in the first group of the periodic table

Explanation:
1. Hydrogen has one valence electron like alkali metals and needs one electron to complete its duplet like halogens, so statements (a) and (b) are correct.
2. It is the lightest element, so (d) is correct.
3. Hydrogen is conventionally placed in group 1, so the statement that it cannot be placed there is incorrect.

Teacher's Note:
1. H
2. y
3. d
4. r
5. o
6. g
7. e
8. n
9.
10. h
11. a
12. s
13.
14. a
15.
16. u
17. n
18. i
19. q
20. u
21. e
22.
23. p
24. o
25. s
26. i
27. t
28. i
29. o
30. n
31. :
32.
33. i
34. t
35.
36. s
37. h
38. o
39. w
40. s
41.
42. r
43. e
44. s
45. e
46. m
47. b
48. l
49. a
50. n
51. c
52. e
53.
54. t
55. o
56.
57. b
58. o
59. t
60. h
61.
62. g
63. r
64. o
65. u
66. p
67.
68. 1
69.
70. a
71. n
72. d
73.
74. g
75. r
76. o
77. u
78. p
79.
80. 1
81. 7
82. .
83.
84. I
85. t
86.
87. i
88. s
89.
90. s
91. t
92. i
93. l
94. l
95.
96. w
97. r
98. i
99. t
100. t
101. e
102. n
103.
104. a
105. t
106.
107. t
108. h
109. e
110.
111. t
112. o
113. p
114.
115. o
116. f
117.
118. g
119. r
120. o
121. u
122. p
123.
124. 1
125. .

Answer: (a) \( \ce{Mg + H2O} \)

Explanation:
1. Magnesium is more electropositive than hydrogen and displaces it from hot water: \( \ce{Mg + H2O -> MgO + H2} \).
2. The other three reactions are used to prepare hydrogen peroxide, not hydrogen: \( \ce{H2S2O8 + 2H2O -> 2H2SO4 + H2O2} \), \( \ce{BaO2 + 2HCl -> BaCl2 + H2O2} \) and \( \ce{Na2O2 + 2HCl -> 2NaCl + H2O2} \).

Teacher's Note:
1. P
2. e
3. r
4. o
5. x
6. i
7. d
8. e
9. s
10.
11. r
12. e
13. a
14. c
15. t
16.
17. w
18. i
19. t
20. h
21.
22. d
23. i
24. l
25. u
26. t
27. e
28.
29. a
30. c
31. i
32. d
33. s
34.
35. t
36. o
37.
38. g
39. i
40. v
41. e
42.
43. H
44. ₂
45. O
46. ₂
47. ,
48.
49. w
50. h
51. i
52. l
53. e
54.
55. a
56. c
57. t
58. i
59. v
60. e
61.
62. m
63. e
64. t
65. a
66. l
67. s
68.
69. r
70. e
71. a
72. c
73. t
74.
75. w
76. i
77. t
78. h
79.
80. w
81. a
82. t
83. e
84. r
85.
86. o
87. r
88.
89. a
90. c
91. i
92. d
93. s
94.
95. t
96. o
97.
98. g
99. i
100. v
101. e
102.
103. H
104. ₂
105. .
106.
107. L
108. e
109. a
110. r
111. n
112.
113. t
114. h
115. e
116.
117. t
118. w
119. o
120.
121. g
122. r
123. o
124. u
125. p
126. s
127.
128. s
129. e
130. p
131. a
132. r
133. a
134. t
135. e
136. l
137. y
138. .

Answer: (c) 1, 2 and 3

Explanation:
1. Statement 1 is correct: an electric arc dissociates \( \ce{H2} \) into atoms (Langmuir process).
2. Statement 2 is correct: aluminium is too strongly electropositive for hydrogen to reduce its oxide.
3. Statement 3 is correct: palladium occludes up to about 900 times its own volume of hydrogen.
4. Statement 4 is incorrect: sodium reacts with absolute alcohol to give nascent hydrogen, \( \ce{C2H5OH + Na -> C2H5ONa + 1/2 H2} \).
5. So statements 1, 2 and 3 are correct.

Teacher's Note:
1. P
2. a
3. l
4. l
5. a
6. d
7. i
8. u
9. m
10.
11. h
12. y
13. d
14. r
15. i
16. d
17. e
18.
19. f
20. o
21. r
22. m
23. a
24. t
25. i
26. o
27. n
28.
29. i
30. s
31.
32. t
33. h
34. e
35.
36. b
37. a
38. s
39. i
40. s
41.
42. o
43. f
44.
45. h
46. y
47. d
48. r
49. o
50. g
51. e
52. n
53.
54. s
55. t
56. o
57. r
58. a
59. g
60. e
61.
62. a
63. n
64. d
65.
66. p
67. u
68. r
69. i
70. f
71. i
72. c
73. a
74. t
75. i
76. o
77. n
78. .
79.
80. M
81. e
82. t
83. a
84. l
85.
86. o
87. x
88. i
89. d
90. e
91. s
92.
93. o
94. f
95.
96. v
97. e
98. r
99. y
100.
101. a
102. c
103. t
104. i
105. v
106. e
107.
108. m
109. e
110. t
111. a
112. l
113. s
114.
115. s
116. u
117. c
118. h
119.
120. a
121. s
122.
123. A
124. l
125.
126. a
127. r
128. e
129.
130. n
131. o
132. t
133.
134. r
135. e
136. d
137. u
138. c
139. e
140. d
141.
142. b
143. y
144.
145. h
146. y
147. d
148. r
149. o
150. g
151. e
152. n
153. .

Answer: (d) It expresses the kinetics of the reduction process

Explanation:
1. An Ellingham diagram plots \( \Delta_f G^\circ \) against temperature for oxide formation; for most oxides the lines slope upward.
2. Coupling of two reactions to judge feasibility of reduction is read from the diagram.
3. The diagram is purely thermodynamic and says nothing about the rate (kinetics) of reduction, so (d) is incorrect.

Teacher's Note:
1. E
2. l
3. l
4. i
5. n
6. g
7. h
8. a
9. m
10.
11. d
12. i
13. a
14. g
15. r
16. a
17. m
18. s
19.
20. t
21. e
22. l
23. l
24.
25. w
26. h
27. e
28. t
29. h
30. e
31. r
32.
33. a
34.
35. r
36. e
37. d
38. u
39. c
40. t
41. i
42. o
43. n
44.
45. i
46. s
47.
48. p
49. o
50. s
51. s
52. i
53. b
54. l
55. e
56. ,
57.
58. n
59. e
60. v
61. e
62. r
63.
64. h
65. o
66. w
67.
68. f
69. a
70. s
71. t
72.
73. i
74. t
75.
76. o
77. c
78. c
79. u
80. r
81. s
82. .
83.
84. R
85. e
86. m
87. e
88. m
89. b
90. e
91. r
92.
93. t
94. h
95. i
96. s
97.
98. w
99. h
100. e
101. n
102.
103. c
104. h
105. o
106. o
107. s
108. i
109. n
110. g
111.
112. a
113.
114. r
115. e
116. d
117. u
118. c
119. i
120. n
121. g
122.
123. a
124. g
125. e
126. n
127. t
128.
129. i
130. n
131.
132. m
133. e
134. t
135. a
136. l
137. l
138. u
139. r
140. g
141. y
142. .

Answer: (d) LiH > NaH > KH > RbH > CsH

Explanation:
1. As we go down group 1 the metal size increases and the M–H bond becomes weaker.
2. Hence thermal stability falls from Li to Cs.
3. The order is LiH > NaH > KH > RbH > CsH.

Teacher's Note:
1. S
2. t
3. a
4. b
5. i
6. l
7. i
8. t
9. y
10.
11. o
12. f
13.
14. i
15. o
16. n
17. i
18. c
19.
20. h
21. y
22. d
23. r
24. i
25. d
26. e
27. s
28.
29. f
30. o
31. l
32. l
33. o
34. w
35. s
36.
37. l
38. a
39. t
40. t
41. i
42. c
43. e
44.
45. e
46. n
47. e
48. r
49. g
50. y
51. ,
52.
53. w
54. h
55. i
56. c
57. h
58.
59. d
60. r
61. o
62. p
63. s
64.
65. a
66. s
67.
68. t
69. h
70. e
71.
72. c
73. a
74. t
75. i
76. o
77. n
78.
79. g
80. r
81. o
82. w
83. s
84.
85. l
86. a
87. r
88. g
89. e
90. r
91. .
92.
93. L
94. i
95. H
96.
97. i
98. s
99.
100. t
101. h
102. e
103.
104. m
105. o
106. s
107. t
108.
109. s
110. t
111. a
112. b
113. l
114. e
115.
116. a
117. n
118. d
119.
120. C
121. s
122. H
123.
124. t
125. h
126. e
127.
128. l
129. e
130. a
131. s
132. t
133. .

Answer: (c) Melts of ionic hydrides conduct electricity and liberate dihydrogen gas at the cathode

Explanation:
1. Statements (a) and (b) correctly describe ionic (saline) hydrides.
2. In the molten state the hydride ion \( \ce{H^-} \) is discharged at the anode, not the cathode: \( \ce{2H^- -> H2 + 2e^-} \).
3. So only statement (c) is incorrect and option (d) is wrong because (a) is correct.

Teacher's Note:
1. A
2. n
3. i
4. o
5. n
6. s
7.
8. a
9. l
10. w
11. a
12. y
13. s
14.
15. m
16. i
17. g
18. r
19. a
20. t
21. e
22.
23. t
24. o
25.
26. a
27. n
28. d
29.
30. a
31. r
32. e
33.
34. o
35. x
36. i
37. d
38. i
39. s
40. e
41. d
42.
43. a
44. t
45.
46. t
47. h
48. e
49.
50. a
51. n
52. o
53. d
54. e
55. .
56.
57. T
58. h
59. e
60.
61. h
62. y
63. d
64. r
65. i
66. d
67. e
68.
69. i
70. o
71. n
72.
73. t
74. h
75. e
76. r
77. e
78. f
79. o
80. r
81. e
82.
83. g
84. i
85. v
86. e
87. s
88.
89. h
90. y
91. d
92. r
93. o
94. g
95. e
96. n
97.
98. g
99. a
100. s
101.
102. a
103. t
104.
105. t
106. h
107. e
108.
109. a
110. n
111. o
112. d
113. e
114. .

Answer: (b) \( \ce{Ca^2+} \) ions

Explanation:
1. Hardness is due to \( \ce{Ca^2+} \) and \( \ce{Mg^2+} \) ions.
2. Zeolite exchanges its \( \ce{Na+} \) for these cations: \( \ce{Na2-zeolite + CaCl2 -> Ca-zeolite + 2NaCl} \).
3. The permutit (zeolite) process thus softens water.

Teacher's Note:
1. Z
2. e
3. o
4. l
5. i
6. t
7. e
8.
9. i
10. s
11.
12. a
13.
14. c
15. a
16. t
17. i
18. o
19. n
20.
21. e
22. x
23. c
24. h
25. a
26. n
27. g
28. e
29. r
30. ,
31.
32. s
33. o
34.
35. o
36. n
37. l
38. y
39.
40. c
41. a
42. t
43. i
44. o
45. n
46. s
47.
48. a
49. r
50. e
51.
52. s
53. w
54. a
55. p
56. p
57. e
58. d
59. .
60.
61. I
62. t
63.
64. c
65. a
66. n
67.
68. b
69. e
70.
71. r
72. e
73. g
74. e
75. n
76. e
77. r
78. a
79. t
80. e
81. d
82.
83. b
84. y
85.
86. w
87. a
88. s
89. h
90. i
91. n
92. g
93.
94. w
95. i
96. t
97. h
98.
99. s
100. o
101. d
102. i
103. u
104. m
105.
106. c
107. h
108. l
109. o
110. r
111. i
112. d
113. e
114.
115. s
116. o
117. l
118. u
119. t
120. i
121. o
122. n
123. .

Answer: (d) A is false, but R is true.

Explanation:
1. In HOF the bond angle is about 97°, whereas in HOCl it is about 103°, so the assertion is false.
2. Oxygen is more electronegative than Cl, Br and I but less electronegative than fluorine, so the reason is also false.
3. Both statements are incorrect.

Teacher's Note:
1. E
2. l
3. e
4. c
5. t
6. r
7. o
8. n
9. e
10. g
11. a
12. t
13. i
14. v
15. i
16. t
17. y
18.
19. o
20. r
21. d
22. e
23. r
24.
25. i
26. s
27.
28. F
29.
30. >
31.
32. O
33.
34. >
35.
36. C
37. l
38. .
39.
40. A
41. l
42. w
43. a
44. y
45. s
46.
47. c
48. h
49. e
50. c
51. k
52.
53. e
54. x
55. c
56. e
57. p
58. t
59. i
60. o
61. n
62. s
63.
64. s
65. u
66. c
67. h
68.
69. a
70. s
71.
72. f
73. l
74. u
75. o
76. r
77. i
78. n
79. e
80.
81. b
82. e
83. f
84. o
85. r
86. e
87.
88. a
89. c
90. c
91. e
92. p
93. t
94. i
95. n
96. g
97.
98. a
99.
100. g
101. e
102. n
103. e
104. r
105. a
106. l
107.
108. s
109. t
110. a
111. t
112. e
113. m
114. e
115. n
116. t
117. .

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Explanation:
1. Hydrogen can lose its electron to form \( \ce{H+} \), gain one to form \( \ce{H-} \) (ionic hydrides) or share it to form covalent bonds.
2. Both ionic (electrovalent) and covalent bonding therefore occur, which is exactly why it can combine in all three ways.
3. Both statements are true and the reason explains the assertion.

Teacher's Note:
1. H
2. y
3. d
4. r
5. o
6. g
7. e
8. n
9.
10. f
11. o
12. r
13. m
14. s
15.
16. i
17. o
18. n
19. i
20. c
21.
22. h
23. y
24. d
25. r
26. i
27. d
28. e
29. s
30.
31. w
32. i
33. t
34. h
35.
36. a
37. c
38. t
39. i
40. v
41. e
42.
43. m
44. e
45. t
46. a
47. l
48. s
49.
50. a
51. n
52. d
53.
54. c
55. o
56. v
57. a
58. l
59. e
60. n
61. t
62.
63. h
64. y
65. d
66. r
67. i
68. d
69. e
70. s
71.
72. w
73. i
74. t
75. h
76.
77. n
78. o
79. n
80. -
81. m
82. e
83. t
84. a
85. l
86. s
87. .
88.
89. I
90. t
91. s
92.
93. t
94. h
95. r
96. e
97. e
98.
99. b
100. o
101. n
102. d
103. i
104. n
105. g
106.
107. m
108. o
109. d
110. e
111. s
112.
113. f
114. o
115. l
116. l
117. o
118. w
119.
120. d
121. i
122. r
123. e
124. c
125. t
126. l
127. y
128.
129. f
130. r
131. o
132. m
133.
134. t
135. h
136. i
137. s
138. .