Chemistry

Oxidation States and Oxides

334 Questions

Oxidation states represent the degree of oxidation of an atom in a chemical compound. This topic covers calculating valency, classifying oxides as acidic or basic, and understanding thermal decomposition. These concepts are frequently tested in chemistry sections across multiple competitive examination platforms.

calculating oxidation statesclassification of oxidesvalency determinationthermal decompositionstability of metal oxides

Oxidation States and Oxides Questions

Multiple choice

Match the column – I (third row transition metals) with column – II (their most stable oxidation state) and select the correct option.

 
Column – I
Column – II
P. Lanthanum 1. +3
Q. Hafnium 2. +4
R. Tantalum 3. +5

  1. P - 1, Q - 2, R - 3

  2. P - 1, Q - 3, R - 2

  3. P - 2, Q - 1, R - 3

  4. P - 3, Q - 1, R - 2

  5. P - 3, Q - 2, R - 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The most stable oxidation state of lanthanum (La) is +3 The most stable oxidation state of hafnium (Hf) is +4 The most stable oxidation state of tantalum (Ta) is +5

Multiple choice

Which of the following pairs is correctly matched?

  1. Covalent character: MI > MBr > MCl > MF

  2. Stability of +1 oxidation state: In < Ga < Al < Tl

  3. Most stable form of phosphorus: White phosphorus

  4. Ionic size: S2- > Cl- > K+ > Ca2+

  5. Acidic strength: HClO > HIO > HBrO
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct order of covalent character is: MI > MBr > MCl > MF. As the size of the anion decreases, covalency decreases.

Multiple choice

ASSERTION (A): Zn does not exist in variable oxidation states. REASON (R): All orbitals in Zn are completely filled with paired electrons.

In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:

1. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. 1

  2. 2

  3. 3

  4. 4

  5. 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Assertion as well as reason statements are correct and R is the correct explanation of A. Zn does not exist in variable oxidation states. The oxidation state of an element depends on its electronic configuration. Zn: [Ar] 3d10, 4s2 When Zn loses two electrons from 4s-orbital, it gets a very stable electronic configuration where all the electrons are paired in the d-orbital, giving +2 oxidation state. Zn2+: [Ar] 3d10 Since all orbitals are completely filled with paired electrons, it has a very stable electronic configuration.Therefore, Zn shows only one oxidation state of +2.

Multiple choice

Oxidation is a process which involves

  1. the loss of electrons

  2. the gain of hydrogen

  3. the gain of electrons

  4. no change in electrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In chemical terms, oxidation is defined as the loss of electrons, while reduction is the gain of electrons.

Multiple choice

In O2 the atomicity of oxygen is

  1. 2

  2. 1

  3. 3

  4. 4

  5. 8
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atomicity is the number of atoms of an element present in one molecule of that element. They can be monoatomic (He), diatomic (H2), triatomic (O3) and polyatomic (S8). Homoatomic molecules have different atomicity; so option (1) is the answer.

Multiple choice

How many peroxide linkages are present in S2O8-2?

  1. 1

  2. 2

  3. 3

  4. 5

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because , S2O8-2, is a dimerize form of  SO4-2 in which one O - atom of each sulphate ion link together to form dimer and that linkage is peroxide linkage and  only one linkage is persent in this ion.  

Multiple choice

The number of electrons that are involved in the reduction of permanganate to manganese (II) salt, manganate and manganese dioxide respectively are __________.

  1. 5, 1 and 3

  2. 5, 3 and 1

  3. 2, 7 and 1

  4. 2, 3 and 1

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct  because in reduction of permanganate ion to manganese (II) salt, 5 electrons are involved,  In case of the manganate ions, 3 electrons are involved and in manganese oxide, only 1 electron is involved.