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

Which of the following pair of transition metal oxides is likely to be categorized as semiconductors?

  1. FeO, VO

  2. Fe2O3, CrO2

  3. V2O5, Mn2O3

  4. Mn2O3, VO

  5. CuO, MnO
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When potential difference is applied to mobile electrons, they conduct electric current. In this case the energy band gap is very low or zero, hence such type of molecules are called metallic or good conductors to electricity (like - VO, TiO, CrO2, etc.). If the energy band gap is  more than that of metallic conductors they are reffered to as semiconductor, i.e., FeO, V2O5, Mn2O3, CuO, etc. If the energy band gap is very large, the molecules are called as insulators like - MnO. Hence, V2O5 and Mn2O3 are both categorized as semiconductors.

Multiple choice

What is the name of the compound HgO?

  1. Hydragyrium oxide

  2. Mercurous oxide

  3. Mercuric oxide

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

Valency of oxygen is - 2 and that of mercury is + 2. Therefore, name of the compound is mercuric oxide.

Multiple choice

When small amount of sodium oxide is dissolved in water, then

  1. oxidation number of sodium decreases

  2. oxide ion accepts sharing in a pair of electrons

  3. oxide ion donates a pair of electrons

  4. oxidation number of oxygen increases

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

Oxide ion donates a pair of electrons, thus changes to hydroxide ion. 

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Among ${ KO } _{ 2 },{ AIO } _{ 2 }^{ - },{ BaO } _{ 2 }\ and\ { NO } _{ 2 }^{ + }$, unpaired electron is present in :

  1. ${ NO } _{ 2 }^{ + }\quad and\quad { BaO } _{ 2 }$
  2. ${ KO } _{ 2 }\quad and\quad AI{ O } _{ 2 }^{ - }$
  3. ${ KO } _{ 2 }$ only
  4. $Ba{ O } _{ 2 }$ only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This can be done by counting number of valence electrons


$KO _2=1+2\times 6=17$-Odd number of electrons and hence unpaired.


$AlO^{2-} _2=3+2\times 6+1=14$-Even number of electrons and hence paired.

$BaO _2=2+2\times6=14$-Even number of electrons and hence paired.

$NO^{+} _{2}=5+2\times6 -1=16$-Even number of electrons and hence paired.

Hence option C is the correct answer.