Chemistry

Oxidation States and Oxides

308 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

What is the oxidation sate of K in KO2?

  1. +2

  2. -2

  3. +1

  4. -1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because superoxide species is represented as O2- since compound on a awhole is neutral hence oxidation state of potassium is +1.

Multiple choice

Identify the incorrect statement(s). (P) The central metal atom shows +VI oxidation state in potassium chromate and potassium dichromate. (Q) Limonite and willemenite are ores of zinc. (R) Zinc oxide is called as white lead and used as a whitening material.

  1. P only

  2. Q only

  3. R only

  4. P and Q only

  5. Q and R only
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

P. The central metal atom in potassium chromate and potassium dichromate is Cr. Chromium has +VI oxidation state in K2CrO4 and K2Cr2O7. Q. Limonite (Fe2O3.3H2O) is an ore of iron and willemite is an ore of zinc. R. Zinc oxide is an inorganic compound with the formula ZnO. ZnO is a white powder that is insoluble in water, and it is widely used as an additive in numerous materials and products including rubbers, plastics, ceramics, glass, cement, etc. White lead (PbCO3).2Pb(OH)2 is a complex chemical compound containing both a carbonate and a hydroxide portion and occurs naturally as a mineral for lead. White lead compounds were used as pigmenting materials like cement, lubricants, etc. but due to its toxicity, it is not used frequently.  Hence, both the statements Q and R are incorrect.

Multiple choice

Match the column – I (transition metal element) with column – II (most stable oxidation state) and select the correct option.

 
Column – I
Column – II
P. Cadmium 1. +1
Q. Ruthenium 2. +2
R. Silver 3. +3
S. Zirconium 4. +4

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

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

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

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

  5. P - 4, Q - 2, R - 3, S - 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The most stable oxidation state of cadmium is +2. The most stable oxidation state of silver is +1. The most stable oxidation state of ruthenium is +3. The most stable oxidation state of zirconium is +4.

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.