Assignment Sem1ch4 Chemistry
1.
2.
3.
4.
5.
The oxidation number of C in CO 2 is
(a) – 2
(b) + 2
(c) – 4
(d) + 4
The oxidation number of As is
(a) + 2 and + 3
(b) + 3 and + 5
(c) + 3 and + 4
(d) None of these
The oxidation number of Ba in barium peroxide is
(a) + 6
(b) + 2
(c) 1
(d) + 4
HNO 2 acts both as reductant and oxidant, while HNO 3 acts only as oxidant. It is due to their
(a) Solubility ability
(b) Maximum oxidation number
(c) Minimum oxidation number
(d) Minimum number of valence electrons
Chlorine is in +1 oxidation state in
(a) HCl
(b) HClO4
(c) ICl
(d) Cl 2 O
9.
The valency of Cr in the complex [Cr(H 2 O)4 Cl 2 ]
(a) 1
(b) 3
(c) 5
(d) 6
In the conversion Br2  BrO3 , the oxidation state of bromine changes from
(a) – 1 to – 1
(b) 0 to – 1
(c) 0 to + 5
(d) 0 to – 5
In the chemical reaction Cl 2  H 2 S  2 HCl  S , the oxidation number of sulphur changes from
(a) 0 to 2
(b) 2 to 0
(c) – 2 to 0
(d) – 2 to – 1
Oxidation number of cobalt in K[Co (CO )4 ] is
10.
(a) + 1
(b) + 3
(c) – 1
(d) – 3
When K 2 Cr2 O7 is converted to K 2 CrO4 , the change in the oxidation state of chromium is
6.
7.
8.
11.
12.
13.
14.
(a) 0
(b) 6
(c) 4
(d) 3
The oxidation number of chlorine in HOCl
(a) – 1
(b) 0
(c) + 1
(d) + 2
Oxidation number of S in S 2  is
(a) – 2
(b) 0
(c) – 6
(d) + 2
Oxidation number of N in (NH 4 )2 SO 4 is
(a) – 1 / 3
(b) – 1
(c) + 1
(d) – 3
In which compound, oxidation state of nitrogen is 1
(a) NO
(b) N 2 O
(c) NH 2 OH
(d) N 2 H 4
15.
Oxidation number of nickel in Ni(CO )4
16.
(a) 0
(b) + 4
(c) – 4
(d) + 2
The oxidation number of sulphur in H 2 SO 4 is
18.
(a) – 2
(b) + 2
(c) + 4
(d) + 6
Oxidation state of chlorine in perchloric acid is
(a) – 1
(b) 0
(c) – 7
(d) + 7
Oxidation number of N in HNO 3 is
19.
(a) – 3.5
(b) + 3.5
(c) – 3, +5
(d) + 5
The oxidation number of Mn in MnO41 is
17.
21.
(a) + 7
(b) – 5
(c) + 6
(d) + 5

Sn loses two electrons in a reaction. What will be the oxidation number of tin after the reaction
(a) + 2
(b) Zero
(c) + 4
(d) – 2
The oxidation state of Mn in K 2 MnO4
22.
(a) + 2
(b) + 7
(c) – 2
(d) + 6
Oxidation number of oxygen in O 2 molecule is
20.
23.
24.
(a) + 1
(b) 0
(c) + 2
(d) – 2
Maximum oxidation state of Cr is
(a) 3
(b) 4
(c) 6
(d) 7
In which of the following compound transition metal has zero oxidation state
(a) CrO5
(b) NH 2 .NH 2
(c) NOClO4
25.
(d) [Fe(CO )5 ]
Carbon is in the lowest oxidation state in
(a) CH 4
(b) CCl 4
(c) CF4
(d) CO 2
26.
Oxidation number of carbon in H 2 C 2 O4 is
27.
(a) + 4
(b) + 3
(c) + 2
(d) – 2
The oxidation number of Pt in [Pt(C 2 H 4 ) Cl 3 ] is
28.
(a) + 1
(b) + 2
(c) + 3
(d) + 4
The oxidation number of carbon in CH 2 Cl 2 is
31.
(a) 0
(b) + 2
(c) 2
(d) + 4
The oxidation states of phosphorus vary from
(a) – 3 to +5
(b) – 1 to +1
(c) – 3 to +3
(d) – 5 to +1
The process in which oxidation number increases is known as
(a) Oxidation
(b) Reduction
(c) Auto-oxidation
(d) None of the above
The oxidation number of S in H 2 S 2O8 is
32.
(a) + 2
(b) + 4
(c) + 6
(d) + 7
The oxidation state of nitrogen in N 3 H is
29.
30.
(a) 
1
3
(c) 1
33.
(b) + 3
(d) 
1
3
Which of the following statements is correct
(a) Hydrogen has oxidation number 1 and  1
(b)
Hydrogen has same electronegativity as halogens
(c) Hydrogen will not be liberated at anode
(d)
Hydrogen has same ionization potential as alkali metals
34.
The oxidation state of Cr in [Cr(NH 3 )4 Cl 2 ] is
35.
(a) +3
(b) +2
(c) +1
(d) 0
Sulphur has highest oxidation state in
(a) SO 2
(b) H 2 SO 4
(c) Na 2 S 2 O3
36.
(d) Na 2 S 4 O6
The oxidation number of Fe and S in iron pyrites are
(a) 4, – 2
(b) 2, – 1
(c) 3, – 1.5
(d) 3, – 1
37.
38.
39.
40.
The oxidation number of nitrogen in NO 3 is
(a) – 1
(b) + 2
(c) + 3
(d) + 5
Oxidation state of elemental carbon is
(a) 0
(b) 1
(c) 2
(d) 3
The sum of the oxidation numbers of all the carbons in C6 H 5 CHO is
(a) + 2
(b) 0
(c) + 4
(d) – 4
Which one of the following has the highest oxidation number of iodine
(a) KI 3
(b) KI
(c) IF5
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
(d) KIO4
The oxidation number of N in N 2 H 5
(a) – 3
(b) (– 2)
(c) – 1
(d) + 2
In which of the following compounds the oxidation number of carbon is maximum
(a) HCHO
(b) CHCl 3
(c) CH 3 OH
(d) C12 H 22 O11
The oxidation state of chlorine in KClO4 is
(a) – 1
(b) + 1
(c) + 7
(d) – 7
The oxidation state of I in H 4 IO6 is
(a) + 7
(b) + 5
(c) + 1
(d) – 1
An element which never has a positive oxidation number in any of its compounds
(a) Boron
(b) Oxygen
(c) Chlorine
(d) Fluorine
In an oxidation process, oxidation number
(a) Decreases
(b) Increases
(c) Does not change
(d) First increases then decreases
If HNO 3 changes into N 2 O , the oxidation number is changed by
(a) + 2
(b) – 1
(c) 0
(d) + 4
The characteristic oxidation number of atoms in free metals is
(a) Minus one
(b) Any number
(c) One
(d) Zero
In which one of the following changes there are transfer of five electrons
(a) MnO4  Mn 2 
(b) CrO42  Cr 3 
(c) MnO42   MnO2
(d) Cr2 O72   2Cr 3 
Oxidation number of C in C6 H12 O6 is
(a) + 6
(b) – 6
(c) 0
(d) + 4
In which of the following compounds iron has lowest oxidation state
(a) FeSO 4 .( NH 4 )2 SO 4 .6 H 2 O
(b) K 4 Fe(CN )6
(c) Fe(CO )5
(d) Fe2 O
(e) K 2 FeO4
The oxidation number of hydrogen in MH 2 is
(a) + 1
(b) – 1
(c) + 2
(d) – 2
Oxidation number of iodine varies from
(a) – 1 to +1
(b) – 1 to +7
(c) +3 to +5
(d) – 1 to +5
When SO 2 is passed through acidic solution of potassium dichromate, then chromium sulphate is formed. Change in valency of
chromium is
(a) +4 to +2
(b) +5 to +3
(c) +6 to +3
(d) +7 to +2
55.
56.
The oxidation states of the most electronegative element in the products of the reaction of BaO2 with dilute H 2 SO 4 are
(a) 0 and – 1
(b) – 1 and – 2
(c) – 2 and 0
(d) – 2 and + 1
The highest oxidation state of Mn is shown by
(a) K 2 MnO4
(b) KMnO4
(c) MnO2
57.
58.
59.
60.
(e) MnO
The oxidation number of carbon in CH 2 O is
(a) – 2
(b) + 2
(c) 0
(d) + 4
Oxidation state of oxygen in hydrogen peroxide is
(a) – 1
(b) + 1
(c) 0
(d) – 2
The oxidation number of Cr in K 2 Cr2 O7 is
(a) +6
(b) – 7
(c) +2
(d) – 2
In which of the following compounds transition metal is in oxidation state zero
(a) [Co (NH 3 )6 ]Cl 2
(b) [Fe(H 2 O)6 SO 4 ]
(c) [ Ni(CO )4 ]
61.
(d) Mn2 O2
(d) [Fe(H 2 O)3 ](OH )2
Oxidation number of osmium (Os) in OsO4 is
63.
(a) + 4
(b) + 6
(c) + 7
(d) + 8
The atomic number of an element which shows the oxidation state of + 3 is
(a) 13
(b) 32
(c) 33
(d) 17
The oxidation number of iron in the compound K 4 [Fe(CN )6 ] is
64.
(a) + 6
(b) + 4
(c) + 3
(d) + 2
The brown ring complex compound is formulated as [Fe(H 2 O)5 NO ] SO 4 . The oxidation state of iron is
65.
(a) 1
(b) 2
(c) 3
(d) 0
Oxidation state of oxygen in F2 O is
62.
66.
67.
68.
69.
70.
71.
72.
73.
74.
(a) + 1
(b) + 2
(c) 1
(d) 2
Phosphorus has the oxidation state of +3 in
(a) Orthophosphoric acid (b) Phosphorus acid
(c) Metaphosphoric acid (d) Pyrophosphoric acid
Oxidation number of P in Mg2 P2 O7 is
(a) + 3
(b) + 2
(c) + 5
(d) – 3
The oxidation state of nitrogen is highest in
(a) N 3 H
(b) NH 2 OH
(c) N 2 H 4
(d) NH 3
Oxidation number of P in KH 2 PO2 is
(a) + 1
(b) + 3
(c) + 5
(d) – 4
The most common oxidation state of an element is –2. The number of electrons present in its outermost shell is
(a) 4
(b) 2
(c) 6
(d) 8
Sulphur has lowest oxidation number in
(a) H 2 SO 3
(b) SO 2
(c) H 2 SO 4
(d) H 2 S
The oxidation number and covalency of sulphur in the sulphur molecule (S 8 ) are respectively
(a) 0 and 2
(b) 6 and 8
(c) 0 and 8
(d) 6 and 2
In ferrous ammonium sulphate oxidation number of Fe is
(a) + 3
(b) + 2
(c) + 1
(d) – 2
The oxidation number of nitrogen in NH 2 OH is
(a) + 1
(b) – 1
75.
76.
77.
(c) – 3
(d) – 2
The oxidation number of phosphorus in Ba(H 2 PO2 )2 is
(a) – 1
(b) + 1
(c) + 2
(d) + 3
A compound is in its low oxidation state. Then its will be
(a) Highly acidic
(b) Highly basic
(c) Highest oxidising property
(d) Half acidic, half basic
The oxidation number and the electronic configuration of sulphur in H 2 SO 4 is
(a) + 4; 1s 2 2 s 2 2 p 6 3 s 2
(b) + 2; 1s 2 2 s 2 2 p 6 3 s 2 3 p 2
(c) + 3; 1s 2 2 s 2 2 p 6 3 s 2 3 p1
78.
(d) + 6; 1s 2 2 s 2 2 p 6
The oxidation number of Mn in KMnO4 is
79.
(a) + 7
(b) – 7
(c) + 1
(d) – 1
Oxidation number of As atoms in H 3 AsO4 is
80.
(a) – 3
(b) + 4
(c) + 6
(d) + 5
In XeO 3 and XeF6 the oxidation state of Xe is
81.
(a) + 4
(b) + 6
(c) + 1
(d) + 3
Oxidation number of carbon in CH 3  Cl is
82.
(a) – 3
(b) – 2
(c) – 1
(d) 0
The oxidation state of Cr in Cr2 O72  is
83.
(a) 4
(b) – 6
(c) 6
(d) – 2
Oxidation state of ‘S’ in H 2 SO 3
84.
(a) + 3
(b) + 6
(c) + 4
(d) + 2
Oxidation numbers of two Cl atoms in bleaching powder, CaOCl 2 are
85.
(a) – 1, – 1
(b) + 1, – 1
(c) + 1, + 1
(d) 0, – 1
Select the compound in which chlorine is assigned the oxidation number +5
(a) HClO4
(b) HClO2
(c) HClO3
86.
87.
When KMnO4 is reduced with oxalic acid in acidic solution, the oxidation number of Mn changes from
(a) 7 to 4
(b) 6 to 4
(c) 7 to 2
(d) 4 to 2
Oxygen has oxidation states of +2 in the
(a) H 2 O 2
(b) CO 2
(c) H 2 O
88.
89.
90.
91.
92.
(d) HCl
(d) OF2
The element exhibiting most stable  2 oxidation state among the following is
(a) Ag
(b) Fe
(c) Sn
(d) Pb
Oxidation number of sulphur in S 2 O32  is
(a) – 2
(b) + 2
(c) + 6
(d) 0
Carbon has zero oxidation number in
(a) CO
(b) CH 4
(c) CH 2 Cl 2
(d) CH 3 Cl
Oxidation state of oxygen atom in potassium superoxide is
(a) 0
(b) – 1
(c)  12
(d) – 2
Oxidation number of S in S 2 Cl 2 is
(a) + 1
(b) – 1
93.
(c) + 6
(d) 0
What is the oxidation number of sulphur in Na 2 S 4 O6
(a)
(c)
94.
95.
96.
2
3
3
5
3
2
5
(d)
2
reacts with KI , the oxidation number of Cu changes by
(b)
When CuSO 4
(a) 0
(b) – 1
(c) 1
(d) 2
The oxidation number of N in NH 4 Cl is
(a) + 5
(b) + 3
(c) – 5
(d) – 3
In which reaction there is a change in valency
(a) 2 NO 2  N 2 O4
(b) 2 NO 2  H 2 O  HNO 2  HNO 3
(c) NH 4 OH  NH 4  OH 
(d) CaCO 3  CaO  CO 2
97.
Oxidation state of Fe in Fe3 O 4 is
(a)
(c)
98.
99.
3
2
5
4
4
5
8
(d)
3
(b)
Nitrogen show different oxidation states in the range
(a) 0 to +5
(b) – 3 to + 5
(c) – 5 to + 3
(d) – 3 to + 3
Oxidation number of Mn in K 2 MnO4 and MnSO 4 are respectively
101.
(a) + 7, + 2
(b) + 6, + 2
(c) + 5, + 2
(d) + 2, + 6
Identify the element which can have highest oxidation numbers
(a) N
(b) O
(c) Cl
(d) C
What is the oxidation number of Co in [Co (NH 3 )4 ClNO 2 ]
102.
(a) + 2
(b) + 3
(c) + 4
(d) + 5
The oxidation number of nickel in K 4 [ Ni(CN )4 ] is
103.
(a) – 2
(b) – 1
(c) + 2
(d) 0
The oxidation number of fluorine in F2 O is
104.
(a) – 1
(b) + 1
(c) + 2
(d) – 2
Oxidation number of Fe in K 3 [Fe(CN )6 ] is
105.
(a) + 2
(b) + 3
(c) + 1
(d) + 4
Oxidation number of N in NH 3 is
100.
[CPMT 1982; BHU 1982; EAMCET 1986]
[AMU 1988]
[CPMT 1979; Pb CET 2004]
106.
107.
108.
109.
(a) – 3
(b) + 3
(c) 0
(d) + 5
What is the net charge on ferrous ion
[AFMC 2004]
(a) + 2
(b) + 3
(c) + 4
(d) + 5
Which of the following elements never show positive oxidation number [CPMT 2004]
(a) O
(b) Fe
(c) Ga
(d) F
The oxidation state shown by silicon when it combines with strongly electropositive metals is
(a) – 2
(b) – 4
(c) + 4
(d) – 2
The oxidation number of sulphur in H 2 S is
[MH CET 2004]
[Pb. CET 2002]
(a) – 2
(b) + 3
110.
111.
112.
113.
(c) + 2
(d) – 3
Oxidation number of nitrogen in NaNO 2 is
[Pb. CET 2000]
(a) + 2
(b) + 3
(c) + 4
(d) – 3
Oxidation number of S in SO 42
[BCECE 2005]
(a) + 6
(b) + 3
(c) + 2
(d) – 2
The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate
solution is
[AIEEE 2005]
(a) +4
(b) +6
(c) +2
(d) +3
The oxidation state of I in IPO4 is
(a) +1
(b) +3
(c) +5
(d) +7
Answers
1
d
2
b
3
b
4
b
5
d
6
b
7
c
8
c
9
c
10
a
11
c
12
a
13
d
14
b
15
a
16
d
17
d
18
d
19
a
20
c
21
d
22
b
23
c
24
d
25
a
26
b
27
b
28
a
29
a
30
a
31
c
32
d
33
a
34
a
35
b
36
a
37
d
38
a
39
d
40
d
41
b
42
b
43
c
44
a
45
d
46
b
47
d
48
d
49
a
50
c
51
c
52
b
53
b
54
c
55
b
56
b
57
c
58
a
59
a
60
c
61
d
62
a
63
d
64
b
65
b
66
b
67
c
68
a
69
a
70
c
71
d
72
a
73
b
74
b
75
b
76
c
77
d
78
a
79
d
80
b
81
b
82
c
83
c
84
b
85
c
86
c
87
d
88
d
89
b
90
c
91
c
92
a
93
d
94
c
95
d
96
b
97
d
98
b
99
b
10
0
c
10
1
a
10
2
d
10
3
a
10
4
b
10
5
a
10
6
a
10
7
d
10
8
b
10
9
a
11
0
b
11
1
a
11
2
d
11
3
b