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

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.

Multiple choice

Which of the following statements is incorrect?

  1. Ozone oxidises lead sulphide to lead sulphate.

  2. Ozone oxidises nitric oxide to nitrogen dioxide.

  3. Two oxygen-oxygen bond length in ozone are different.

  4. Options 1 and 2 correct

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

This option is correct because the two O-O atom of the bond length in ozone molecule are same, i.e. 1.278A0 and their bond angle is 116.80.

Multiple choice

Match the Group-I (oxy acids of phosphorus) with Group-II (oxidation state of P atom). ||| |---|---| |Group-I |Group-II| |A. Orthophosphoric acid|1. +1| |B. Hypophosphoric acid|2. +3| |C. Phosphorous acid|3. +4| |D. Metaphosphoric acid|4. +5|

  1. A - 4, B - 3, C - 2, D - 4

  2. A - 2, B - 1, C - 3, D - 4

  3. A - 2, B - 1, C - 4, D - 1

  4. A - 1, B - 2, C - 3, D - 4

  5. A - 4, B - 3, C - 4, D - 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The oxidation state of P in orthophosphoric acid (H3PO4) is +5. The oxidation state of P in phosphorous acid (H3PO3) is +3. The oxidation state of P in hypophosphoric acid (H4P2O6) is +4. The oxidation state of P in metaphosphoric acid (HPO3) is +5. Hence, the correct representation of the codes is A - 4, B - 3, C - 2, D - 4.

Multiple choice

Which type of oxides are formed by Boron?

  1. Amphoteric oxides

  2. Neutral oxide

  3. Basic oxide

  4. Acidic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An oxide that combines with water to give an acid is termed as an acidic oxide. Acidic oxides are the oxides of non-metals. Since boron is a non metal, it forms acidic oxide. Boron oxide(B2O3) is acidic and reacts with water to reform boric acid. When combined with water, acidic oxides produce acids. Acidic oxides are, therefore, known as acid anhydrides, e.g., sulphur dioxide is sulphurous anhydride; sulphur trioxide is sulphuric anhydride.

Multiple choice

In Ostwald's process element used to oxide NH3 is

  1. Fe

  2. V2O5

  3. Pt

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

In Ostwald's  process, Ammonia is converted to nitric acid in two stages. It is oxidized by heating with oxygen in the presence of a catalyst of platinum with 10% rhodium, to form nitric oxide and water. This step is stongly exothermic, making it a useful heat source once initiated (delta H = -950 kJ).