Chem Brain

Question#1

The oxidation state of I in IPO₄ is [Orissa JEE 2005]

+1

+3

+5

+7

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Question#2

The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate solution is [AIEEE 2005]

+4

+6

+2

+3

Please select an option

Question#3

+ 6

+ 3

+ 2

– 2

Please select an option

Question#4

Oxidation number of nitrogen in NaNO₂ is [Pb. CET 2000]

+ 2

+ 3

+ 4

– 3

Please select an option

Question#5

The oxidation number of sulphur in H₂S is [Pb. CET 2002]

– 2

+ 3

+ 2

– 3

Please select an option

Question#6

The oxidation state shown by silicon when it combines with strongly electropositive metals is [MH CET 2004]

– 2

– 4

+ 4

+ 2

Please select an option

Question#7

Which of the following elements never show positive oxidation number [CPMT 2004]

O

Fe

Ga

F

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Question#8

What is the net charge on ferrous ion [AFMC 2004]

+ 2

+ 3

+ 4

+ 5

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Question#9

Oxidation number of N in NH₃ is [CPMT 1979; Pb CET 2004]

– 3

+ 3

0

+5

Please select an option

Question#10

+ 2

+ 3

+ 1

+ 4

Please select an option

Question#11

The oxidation number of fluorine in F₂O is [CPMT 1982; BHU 1982; EAMCET 1986]

– 1

+ 1

+ 2

– 2

Please select an option

Question#12

– 2

– 1

+ 2

0

Please select an option

Question#13

+ 2

+ 3

+ 4

+ 5

Please select an option

Question#14

Identify the element which can have highest oxidation numbers[AIIMS 1996]

N

O

Cl

C

Please select an option

Question#15

Oxidation number of Mn in K₂MnO₄ and MnSO₄ are respectively [CPMT 1997]

+ 7, + 2

+ 6, + 2

+ 5, + 2

+ 2, + 6

Please select an option

Question#16

Nitrogen show different oxidation states in the range [Kerala (Med.) 2003]

0 to +5

– 3 to + 5

– 5 to + 3

– 3 to + 3

Please select an option

Question#17

Oxidation state of Fe in Fe₃O₄ is [CBSE PMT 1999; AIIMS 2002]

Please select an option

Question#18

In which reaction there is a change in valency [NCERT 1971; CPMT 1971]

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Question#19

The oxidation number of N in NH₄Cl is

+ 5

+ 3

– 5

– 3

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Question#20

When CuSO₄ reacts with KI , the oxidation number of Cu changes by [BHU 1997]

0

– 1

1

2

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Question#21

What is the oxidation number of sulphur in Na₂S₄O₆ [AIIMS 1998; DCE 1999]

Please select an option

Question#22

Oxidation number of S in S₂Cl₂ is

+ 1

– 1

+6

0

Please select an option

Question#23

Oxidation state of oxygen atom in potassium superoxide is [MNR 1988; NCERT 1980]

0

– 1

– 2

Please select an option

Question#24

Carbon has zero oxidation number in [Kurukshetra CEE 2002]

CO

CH₄

CH₂Cl₂

CH₃Cl

Please select an option

Question#25

– 2

+ 2

+ 6

0

Please select an option

Question#26

The element exhibiting most stable +2 oxidation state among the following is [IIT 1995]

Ag

Fe

Sn

Pb

Please select an option

Question#27

Oxygen has oxidation states of +2 in the [NCERT 1973; DPMT 1983; MP PET 2000]

H₂O₂

CO₂

H₂O

OF₂

Please select an option

Question#28

When KMnO₄ is reduced with oxalic acid in acidic solution, the oxidation number of Mn changes from [MNR 1987; MP PET 2000; CBSE PMT 2000; UPSEAT 2000, 02; BHU 2003; AMU 2002]

7 to 4

6 to 4

7 to 2

4 to 2

Please select an option

Question#29

Select the compound in which chlorine is assigned the oxidation number +5 [NCERT 1984, 94]

HClO₄

HClO₂

HClO₃

HCl

Please select an option

Question#30

Oxidation numbers of two Cl atoms in bleaching powder, CaOCl₂ are

– 1, – 1

+ 1, – 1

+ 1, + 1

0, – 1

Please select an option

Question#31

Oxidation state of ‘S’ in H₂SO₃ [RPET 2003]

+ 3

+ 6

+ 4

+ 2

Please select an option

Question#32

4

– 6

6

– 2

Please select an option

Question#33

Oxidation number of carbon in CH - Cl₃ is [MP PET 2000]

– 3

– 2

– 1

0

Please select an option

Question#34

In XeO₃ and XeF₆ the oxidation state of Xe is [MP PET 2003]

+ 4

+ 6

+ 1

+ 3

Please select an option

Question#35

Oxidation number of As atoms in H₃AsO₄ is [DPMT 2001]

– 3

+ 4

+ 6

+ 5

Please select an option

Question#36

The oxidation number of Mn in KMnO₄ is [CPMT 1982, 83; EAMCET 1992, 93; RPET 1999]

+ 7

- 7

+ 1

-1

Please select an option

Question#37

The oxidation number and the electronic configuration of sulphur in H₂SO₄ is [KCET 2002]

Please select an option

Question#38

A compound is in its low oxidation state. Then its will be [DCE 2001]

Highly acidic

Highly basic

Highest oxidising property

Half acidic, half basic

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Question#39

The oxidation number of phosphorus in Ba(H₂PO₂ )₂ is [Kurukshetra CEE 1998; DCE 2004]

– 1

+ 1

+ 2

+ 3

Please select an option

Question#40

The oxidation number of nitrogen in NH₂OH is [NCERT 1981]

+ 1

– 1

– 3

– 2

Please select an option

Question#41

In ferrous ammonium sulphate oxidation number of Fe is [CPMT 1988]

+ 3

+ 2

+ 1

– 2

Please select an option

Question#42

The oxidation number and covalency of sulphur in the sulphur molecule ( S₈ ) are respectively [NCERT 1977]

0 and 2

6 and 8

0 and 8

6 and 2

Please select an option

Question#43

Sulphur has lowest oxidation number in [EAMCET 1993]

H₂SO₃

SO₂

H₂SO₄

H₂S

Please select an option

Question#44

The most common oxidation state of an element is –2. The number of electrons present in its outermost shell is [BHU 1983; NCERT 1974; CPMT 1977]

4

2

6

8

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Question#45

Oxidation number of P in KH₂PO₂ is [CPMT 1987; MH CET 1999]

+ 1

+ 3

+ 5

-4

Please select an option

Question#46

The oxidation state of nitrogen is highest in [MP PMT 2001; BHU 2002]

N₃H

NH₂OH

N₂H₄

NH₃

Please select an option

Question#47

Oxidation number of P in Mg₂P₂O₇ is [CPMT 1989; MP PMT 1995]

+ 3

+ 2

+ 5

– 3

Please select an option

Question#48

Phosphorus has the oxidation state of +3 in [NCERT 1982; RPMT 1999]

Orthophosphoric acid

Phosphorus acid

Metaphosphoric acid

Pyrophosphoric acid

Please select an option

Question#49

Oxidation state of oxygen in F₂O is [BHU 1982; UPSEAT 2001; MH CET 2002]

+ 1

+ 2

-1

-2

Please select an option

Question#50

1

2

3

0

Please select an option

Question#51

+ 6

+ 4

+ 3

+ 2

Please select an option

Question#52

The atomic number of an element which shows the oxidation state of + 3 is [CPMT 1989, 94]

13

32

33

17

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Question#53

Oxidation number of osmium (Os) in OsO₄ is [AIIMS 1999]

+ 4

+ 6

+ 7

+ 8

Please select an option

Question#54

In which of the following compounds transition metal is in oxidation state zero [NCERT 1982]

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Question#55

The oxidation number of Cr in K₂Cr₂O₇ is

[CPMT 1981, 85, 90, 93, 99; KCET 1992; BHU 1988, 98; AFMC 1991, 99; EAMCET 1986; MP PMT 1996, 99, 2002; MP PET/PMT 1998; Bihar CEE 1995; RPET 2000]

+6

– 7

+2

– 2

Please select an option

Question#56

Oxidation state of oxygen in hydrogen peroxide is [DPMT 1984; 91; CPMT 1988; MNR 1994; UPSEAT 2001; RPMT 2002; JEE Orissa 2004]

– 1

+ 1

0

-2

Please select an option

Question#57

The oxidation number of carbon in CH₂O is [IIT 1982; EAMCET 1985; MNR 1990; UPSEAT 2001 CPMT 1997, 2004]

– 2

+2

0

+4

Please select an option

Question#58

The highest oxidation state of Mn is shown by [MNR 1983; RPMT 1999]

K₂MnO₄

KMnO₄

MnO₂

Mn₂O₂

MnO

Please select an option

Question#59

The oxidation states of the most electronegative element in the products of the reaction of BaO₂ with dilute H₂SO₄ are [IIT 1991; CBSE PMT 1992; BHU 2000]

0 and – 1

– 1 and – 2

– 2 and 0

– 2 and + 1

Please select an option

Question#60

When SO₂ is passed through acidic solution of potassium dichromate, then chromium sulphate is formed. Change in valency of chromium is [CPMT 1979]

+4 to +2

+5 to +3

+6 to +3

+7 to +2

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Question#61

Oxidation number of iodine varies from [CPMT 1982]

– 1 to +1

– 1 to +7

+3 to +5

– 1 to +5

Please select an option

Question#62

The oxidation number of hydrogen in MH₂ is [CPMT 1976]

+ 1

– 1

+ 2

– 2

Please select an option

Question#63

In which of the following compounds iron has lowest oxidation state[MNR 1984]

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Question#64

Oxidation number of C in C₆H₁₂O₆ is [KCET 1992]

+ 6

- 6

0

+ 4

Please select an option

Question#65

In which one of the following changes there are transfer of five electrons [NCERT 1982]

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Question#66

The characteristic oxidation number of atoms in free metals is [NCERT 1975]

Minus one

Any number

One

Zero

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Question#67

If HNO₃ changes into N₂O , the oxidation number is changed by [BHU 1997; AFMC 2001]

+ 2

-1

0

+ 4

Please select an option

Question#68

In an oxidation process, oxidation number [CPMT 1976]

Decreases

Increases

Does not change

First increases then decreases

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Question#69

An element which never has a positive oxidation number in any of its compounds [AIIMS 1981]

Boron

Oxygen

Chlorine

Fluorine

Please select an option

Question#70

+ 7

+ 5

+ 1

-1

Please select an option

Question#71

The oxidation state of chlorine in KClO₄ is [CPMT 1985]

– 1

+1

+ 7

- 7

Please select an option

Question#72

In which of the following compounds the oxidation number of carbon is maximum

HCHO

CHCl₃

CH₃OH

C₁₂H₂₂O₁₁

Please select an option

Question#73

– 3

(– 2)

– 1

+ 2

Please select an option

Question#74

Which one of the following has the highest oxidation number of iodine [CPMT 1982]

KI₃

KI

IF₅

KIO₄

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Question#75

The sum of the oxidation numbers of all the carbons in C₆H₅CHO is [EAMCET 1986]

+ 2

0

+ 4

-4

Please select an option

Question#76

Oxidation state of elemental carbon is [MNR 1983]

0

1

2

3

Please select an option

Question#77

The oxidation number of nitrogen in NO₃^- is [CPMT 1982]

-1

+ 2

+ 3

+ 5

Please select an option

Question#78

The oxidation number of Fe and S in iron pyrites are

4, – 2

2, – 1

3, – 1.5

3, – 1

Please select an option

Question#79

Sulphur has highest oxidation state in [EAMCET 1991]

SO₂

H₂SO₄

Na₂S₂O₃

Na₂S₄O₆

Please select an option

Question#80

+3

+2

+1

0

Please select an option

Question#81

Which of the following statements is correct [AFMC 1997]

Hydrogen has oxidation number ?1 and ?1

Hydrogen has same electronegativity as halogens

Hydrogen will not be liberated at anode

Hydrogen has same ionization potential as alkali metals

Please select an option

Question#82

The oxidation state of nitrogen in N₃H is [NCERT 1977, 81]

+3

-1

Please select an option

Question#83

+ 2

+ 4

+ 6

+ 7

Please select an option

Question#84

The process in which oxidation number increases is known as [CPMT 1976]

Oxidation

Reduction

Auto-oxidation

None of the above

Please select an option

Question#85

The oxidation states of phosphorus vary from [CPMT 1976]

– 3 to +5

– 1 to +1

– 3 to +3

– 5 to +1

Please select an option

Question#86

The oxidation number of carbon in CH₂Cl₂ is [CPMT 1976; Pb. PET 1999; AFMC 2004]

0

+ 2

- 2

+ 4

Please select an option

Question#87

+ 1

+ 2

+ 3

+ 4

Please select an option

Question#88

Oxidation number of carbon in H₂C₂O₄ is [CPMT 1982]

+ 4

+ 3

+ 2

– 2

Please select an option

Question#89

Carbon is in the lowest oxidation state in [NCERT 1979; MH CET 1999]

CH₄

CCl₄

CF₄

CO₂

Please select an option

Question#90

In which of the following compound transition metal has zero oxidation state [CBSE PMT 1999; BHU 2000]

CrO₅

NH₂.NH₂

NOClO₄

[ Fe(CO)₅]

Please select an option

Question#91

Maximum oxidation state of Cr is [RPMT 2002]

3

4

6

7

Please select an option

Question#92

Oxidation number of oxygen in O₂ molecule is [CPMT 1984]

+ 1

0

+ 2

-2

Please select an option

Question#93

The oxidation state of Mn in K₂MnO₄ [CPMT 1982, 83, 84; DPMT 1982; NCERT 1973; AMU 2000]

+ 2

+ 7

- 2

+ 6

Please select an option

Question#94

Sn⁺⁺ loses two electrons in a reaction. What will be the oxidation number of tin after the reaction

+ 2

Zero

+ 4

– 2

Please select an option

Question#95

+ 7

– 5

+ 6

+ 5

Please select an option

Question#96

Oxidation number of N in HNO3 is [BHU 1997]

– 3.5

+ 3.5

– 3, + 5

+ 5

Please select an option

Question#97

Oxidation state of chlorine in perchloric acid is [EAMCET 1989]

– 1

0

– 7

+ 7

Please select an option

Question#98

The oxidation number of sulphur in H₂SO₄ is [CPMT 1979Pb. CET 2002]

– 2

+ 2

+ 4

+ 6

Please select an option

Question#99

Oxidation number of nickel in Ni(CO)₄ [AIIMS 1984; MNR 1985; CPMT 1997; MP PET/PMT 1998; AMU 2000; 01]

0

+ 4

- 4

+ 2

Please select an option

Question#100

In which compound, oxidation state of nitrogen is 1 [MP PMT 1989]

NO

N₂O

NH₂OH

N₂H₄

Please select an option

Question#101

Oxidation number of N in (NH₄)₂SO₄ is [CPMT 1996]

– 1 / 3

– 1

+ 1

– 3

Please select an option

Question#102

Oxidation number of S in S^2- is [CPMT 1979]

– 2

0

+ 2

+6

Please select an option

Question#103

The oxidation number of chlorine in HOCl

– 1

0

+1

+2

Please select an option

Question#104

When K₂Cr₂O₇ is converted to , K₂CrO₄ the change in the oxidation state of chromium is [NCERT 1981]

0

6

4

3

Please select an option

Question#105

+ 1

+ 3

– 1

– 3

Please select an option

Question#106

0 to 2

2 to 0

– 2 to 0

– 2 to – 1

Please select an option

Question#107

– 1 to – 1

0 to – 1

0 to + 5

0 to – 5

Please select an option

Question#108

1

3

5

6

Please select an option

Question#109

Chlorine is in +1 oxidation state in [MP PMT 1981; NCERT 1974; CPMT 1971, 78]

HCl

HClO₄

ICl

Cl₂O

Please select an option

Question#110

HNO₂ acts both as reductant and oxidant, while HNO₃ acts only as oxidant. It is due to their [AIIMS 2000]

Solubility ability

Maximum oxidation number

Minimum oxidation number

Minimum number of valence electrons

Please select an option

Question#111

The oxidation number of Ba in barium peroxide is [Pb. PMT 2002]

+ 6

+ 2

1

+ 4

Please select an option

Question#112

The oxidation number of As is [RPMT 1997]

+ 2 and + 3

+ 3 and + 5

+ 3 and + 4

None of these

Please select an option

Question#113

The oxidation number of C in CO₂ is [MP PET 2001]

– 2

+ 2

– 4

+ 4

Please select an option

Home/Electrochemistry Oxidation number and Oxidation state

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Oxidation number and Oxidation state