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 chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Most basic oxide among the following is ?

  1. ${{\text{P}} _{\text{2}}}{{\text{O}} _{\text{5}}}$
  2. ${\text{SnO}}$
  3. ${{\text{B}} _{\text{2}}}{{\text{O}} _{\text{3}}}$
  4. ${\text{MgO}}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Basic oxides are typically formed by metals, especially alkali and alkaline earth metals. Among the choices, magnesium oxide (MgO) is a strongly basic metal oxide, whereas P2O5 and B2O3 are acidic, and SnO is amphoteric.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which one of the following is normal oxide?

  1. $K{O _2}$
  2. $Ba{O _2}$
  3. $Si{O _2}$
  4. $Cs{O _2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A normal oxide contains the O(2-) ion. SiO2 is a covalent network solid that behaves as a normal acidic oxide. KO2 and CsO2 are superoxides, and BaO2 is a peroxide.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following is/are peroxide(s) ?

  1. $ PbO _{2} $
  2. $ H _{2}O _{2} $
  3. $ SrO _{2} $
  4. $ BaO _{2} $
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation

In $ {PbO} _{2}, $ Its $ Pb^{+4}$ & $ 2O^{-2} $


In $ {H _{2}O} _{2},$ there is peroxide linkage

$ H-O-O-H $ 

In $ SrO _{2}, $ as Sr is alkaline earth metal 
$ \therefore $ Its $ Sr^{2+} $

$ \therefore $ Its $ O _{2}^{-2}, (\bar{O}-\bar{O}) $ peroxide linkage 

In $ BaO _{2},$ Its $ Ba^{{+2}}\therefore O _{2}^{-2} $

$ \bar{O}-\bar{O} $ peroxide linkage 

Hence, the correct options are $\text{B}$, $\text{C}$ and $\text{D}$

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following oxides is amphoteric in character?

  1. $CaO$
  2. $CO _2$
  3. $SiO _2$
  4. $SnO _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Option (D) is correct.
$SnO _2$ is amphoteric in character.
$SnO _2 + 2NaOH \rightarrow Na _2SnO _3 + H _2O$
$SnO _2 + 4HCl \rightarrow SnCl _4 + 2H _2O$+$CO _2$ is acidic in character.
$SiO _2$ is very weak acid.
$CaO _2$ is basic in nature.
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following oxides is/are not amphoteric in character?

  1. CaO
  2. $CO _2$
  3. $SiO _2$
  4. $SnO _2$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

$CaO$, $CO _2$ and $SiO _2$ when dissolved in water gives base ,hence they are basic oxides.


$SnO _2$ do not react with water, so it is amphoteric. 

Hence options A,B, & C are correct.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following oxides are not neutral?

  1. $CO$
  2. $SnO _2$
  3. $ZnO$
  4. $SiO _2$
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation

 $CO$ is a neutral oxide insoluble in water, but behaves as amphoteric compound. 


$SiO _2$ amphoteric oxide, $SnO _2$ basic oxide and  $ZnO$  is amphoteric oxide.

Hence options B,C & D are correct.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Select the correct statements:

  1. s-block metal oxides are basic in nature, except $BeO$ which is amphoteric.
  2. p-block metal oxides are acidic in nature, except $NO$,$ N _2O$,$ CO$.

  3. d-block metal oxides are basic, acidic, and amphoteric in nature.

  4. d-block metal oxides are only basic in nature.
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

(A) BeO is amphoteric in nature. It reacts with acids as well as alkalies.  Oxides of other s block metal elements are basic in nature. They react only with acids. hence, the option A is correct.

(B) The oxides $NO, N _2O,CO$   are neutral. Whereas the  remaining oxides of p block metals are acidic in nature. Thus, the option B is correct.

Some of the d block metal oxides are basic in nature, some of them acidic in nature where as the rest are amphoteric in nature. Thus, the option C is correct and option D is incorrect.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

The species that do not contain peroxide ions is :

  1. $PbO _2$
  2. $H _2O _2$
  3. $SrO _2$
  4. $BaO _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Only true peroxides which have -O-O- bond give hydrogen peroxide with dilute acids.
$PbO _2$ does not give hydrogen peroxide with dilute acids. So it is not a true peroxide.

Hence option A is correct.

Multiple choice chemistry p-block elements oxides of elements simple oxides oxygen

Which of the following oxides is nuetral?

  1. CO
  2. $SnO _2$

  3. ZnO
  4. $SiO _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Neutral oxides show neither basic nor acidic properties and hence do not form salts when reacted with acids or bases.
  • Carbon and oxygen together have a total of 10 valence electrons in carbon monoxide. To satisfy the octet rule for the carbon, the two atoms form a triple bond, with six shared electrons in three bonding molecular orbitals, rather than the usual double bond found in organic carbonyl compounds. Since four of the shared electrons come from the oxygen atom and only two from carbon, one bonding orbital is occupied by two electrons from oxygen, forming a dative or dipolar bond. This causes a $C\leftarrow O$ polarization of the molecule, with a small negative charge on carbon and a small positive charge on oxygen. Overall the molecule is neutral.
  • Hence option A is correct answer.
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

(1) $N _2 + 2O _2 \leftrightarrow 2NO _2; K _e = 2 \times 10^{-31}$
(2)  $2NO ^+  \leftrightarrow N _2 + O _2;K _e = 2.2 \times 10^{-31}$
(3)  $2N _2O _5 \leftrightarrow 2N _2 + 5O _2 ; K _e = 3.8 \times 10^{-32}$
(4)  $2N _2 + O _2 \leftrightarrow 2N _2O ; K _e = 4 \times 10^{-32}$
From the above data, the most stable oxide is:

  1. $NO _2$
  2. $NO$
  3. $N _2O _5$
  4. $N _2O$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Most stable oxide is that whose  formation const, $K _f$ is largest 

$(1)\ N _2 + 2O _2 \leftrightarrow 2NO _2 $   $K _e = 2 \times 10^{-31}$
                                          $K _f = \sqrt{K _e}$  {$\because$ one mole $NO _2$ must be formed}
                                                $= \sqrt{0.2} \times 10^{-15}$
                                                $\approx 0.44 \times 10^{-15}$
$(2)\ 2NO^+ \leftrightarrow N _2 + O _2 $   $K _e = 2.2 \times 10^{-31}$
                                          $K _f = \dfrac{1}{\sqrt{K _e}} = \dfrac{10^{15}}{\sqrt{0.22}}$
                                                 $\approx 0.13 \times 10^{15}$
$(3)\ 2N _2 O _5 \leftrightarrow 2N _2 + 5O _2$     $K _e = 3.8 \times 10^{-32}$
                                                $K _f = \dfrac{1}{\sqrt{K _e}} \approx 0.512 \times 10^{16}$
$(4)\ 2N _2 + O _2 \leftrightarrow 2N _2O $   $K _e = 4 \times 10^{-32}$
                                          $K _f = \sqrt{K _e} = 2 \times 10^{-16}$
$\therefore N _2O _5$ is most stable.