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

$Na _2O$, $MgO$, $Al _2O _3$ and $SiO _2$ have heat of formation equal to $-416,\ -602,\ -1676$ and $-911$ $ kJ mol^{-1}$ respectively. The most stable oxide is:

  1. $Na _2O$
  2. $MgO$
  3. $Al _2O _3$
  4. $SiO _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$(B)$ A smaller higher charged ion will be closer to the oxide ions $(O^{2-})$, which means the thermal stability of $MgO$ is more or it takes more energy to break the crystal structure of $MgO$
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which one of the following oxides in neutral?

  1. $SiO _7$
  2. $SnO _2$
  3. $ZnO$
  4. $CO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The correct answer is $(B),SnO _2$ 

Because its react with acids as well as with bases to form corresponding salt,
$Sn{O _2} + 2{H _2}S{O _4}\left( {conc.} \right) \to Sn{\left( {S{O _4}} \right) _2} + 2{H _2}O$
and $Sn{\left( {S{O _4}} \right) _2} + 2NaOH \to N{a _2}Sn{O _3} + {H _2}O$ 

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

Two oxides of a metal contain 27.6% and 30.0% of oxygen, respectively. If the formula of the first oxide be ${ { M } _{ 3 }O } _{ 4 }$, find that of the second oxide.

  1. $MO _3$
  2. $M _2O$
  3. $M _2O _3$
  4. $MO$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Given that, formula of first oxide$ = M _3O _4$
Let mass of the metal = x
% of metal in $M _3O _4$ $=\dfrac{3x}{3x+64}\times100$
But  as given % age $= (100-27.6) = 72.4 $%
so, $\dfrac{3x}{3x+64}\times100$ = 72.4
or $x = 56$.
In 2nd oxide,
Given, oxygen = 30%, So metal = 70%
So, the ratio is
$M : O$=$\dfrac{70}{56 }:\dfrac{ 30}{16}$
$\implies 1.25 : 1.875$
$\implies 2 : 3$
So, 2nd oxide is $M _2O _3$
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

The binary compounds of metallic or non-metallic elements with oxygen are called ________.

  1. oxoacid

  2. oxide

  3. oxo

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The binary compound of elements with oxygen is called oxides. Here oxygen is anionic part. So suffix is 'ide'.

Example: Carbon dioxide $CO _2$

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

Oxides which show both acidic and basic nature are called as ______ oxides.

  1. dual

  2. amphoteric

  3. aprotic

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Amphoteric oxides show acidic and basic nature. They react with both acids and bases. 

$Al _2O _3$ is an example of amphoteric oxide.

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

Among the second period which group element form most acidic oxide.

  1. $17^{th}$ group
  2. $14^{th}$ group
  3. $15^{th}$ group
  4. $16^{th}$ group
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Group element having high electronegativity will be most acidic.

And we know group 17 elements are highly electronegative.

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

Metal X form 2 oxide. Formula of ${ 1 }^{ st }$ is ${ XO } _{ 2 }$ ${ 1 }^{ st }$ oxide contain $50\% { O } _{ 2 }$. If ${ 2 }^{ nd }$ oxide contain $60\% { O } _{ 2 }$ .Formula of ${ 2 }^{ nd }$ oxide?

  1. ${ X } _{ 2 }O$
  2. ${ XO } _{ 3 }$
  3. ${ X } _{ 2 }{ O } _{ 3 }$
  4. ${ X } _{ 3 }{ O } _{ 2 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given that in${ XO } _{ 2 },50%$% of $O _2$ is present

${ 2 }O _{ 2 }=32\ \frac { 32 }{ M+32 } =0.5$
now ,given that is second oxide 60% of   is present let no. of metal X contained in this oxide.is n then,
$\cfrac { 32 }{ n\times 32+32 } =0.6\ \cfrac { 1 }{ n+1 } =0.6\ 1=0.6n+0.6\ n=\cfrac { 0.4 }{ 0.6 } =\cfrac { 2 }{ 3 } \ { X } _{ 2 }{ O } _{ 3 }$  
is formula of compound

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

$K0 {2}$(potassium super oxide) is used in oxygen cylinder in space and submarines. This is because it ____________.

  1. absords $CO _{2}$ and increase $O _{2}$ content

  2. eliminates moisture
  3. absords $CO _{2}$

  4. produces ozone
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Because it absorbs $CO _2$ and increases $O _2$ concentration according to the following reaction

$4K{ O } _{ 2 }+2{ CO } _{ 2 }\rightarrow 2{ K } _{ 2 }{ CO } _{ 3 }+3{ O } _{ 2 }$

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

$Pb{O} _{2}$ oxide is:

  1. basic

  2. acidic

  3. neutral

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

The $Pb{ O } _{ 2 }$ behaves as acidic and basic property so it is called as amphoteric.

When $Pb{ O } _{ 2 }$ dissolved in a strong base $Pb{ O }{ H } _{ 6 }$ is obtained so it is an acidic property.
when $Pb{ O } _{ 2 }$ dissolved in HCl,$PbCl _{ 6 }$ is formed so it is a basic property.
Thus $PbO _{ 2 }$ behaves as amphoteric in nature.

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

Which of the following oxide is an amphoteric oxide?

  1. $Bi _{2}O _{3}$
  2. $N _{2}O _{3}$
  3. $P _{4}O _{10}$
  4. $Sb _{2}O _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Those metal oxides which show basic as well as acidic behavior are known as amphoteric oxide
Here ${ Sb } _{ 2 }{ O } _{ 3 }$ oxide is an amphoteric oxide.
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Two metallic oxides contain $27.6$% and $30$% oxygen respectively. If the formula of the first oxide is ${X} _{3}{O} _{4}$, that of the second will be ?

  1. $XO$
  2. $X{O} _{2}$
  3. ${X} _{2}{O} _{5}$
  4. ${X} _{2}{O} _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Solution:

Given that, formula of first oxide = $\\ { M } _{ 3 }{ O } _{ 4 }$

Let mass of the metal = x


% of metal in  $M _{ 3 }O _{ 4 }$ $=\dfrac { 3x }{ 3x+64 } \times 100$


but as given percentage$ =(100-27.6) = 72.4 %$ $\left( \dfrac { 3x }{ 3x+64 }  \right) \times 100=72.4$ or $x=56$


in 2nd oxide

$oxygen$ $=30%$

so for the metal $=70%$


so the ratio is,


$M:O=\dfrac { 70 }{ 56 } :\dfrac { 30 }{ 161.25 } :1.8752:3$ 


 so the second oxide is,


${ M } _{ 2 }{ O } _{ 3 }$


Hence the answer is

${ M } _{ 2 }{ O } _{ 3 }$.(${ X } _{ 2 }{ O } _{ 3 }$)

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

The most acidic oxide among the following is:

  1. $Cl _2O _5$
  2. $Cl _2O$
  3. $Cl _2O _3$
  4. $Cl _2O _7$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Cl _2O _7$ is most acidic because on reacting with water , it gives  most strongest acid than the other three i.e., $HClO _4$ .

So, $Cl _2O _4$ is most acidic 

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

An oxide of element $A$ was analysed and found to have mass ratio of $A$ to oxygen equal to $7:3$. Then formula of oxidation can be :

  1. $A _{3}O _{2}$
  2. $A _{2}O _{3}$
  3. $AO$
  4. $A _{2}O$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mass ratio A:O = 7:3. Moles ratio = (7/AtomicWeightA) : (3/16). If A=56 (Iron), ratio = (7/56) : (3/16) = 0.125 : 0.1875 = 2:3. Formula is A2O3.

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

Titanium oxide $(TiO _{2})$ is heated in stream of hydrogen gas to give water and a new oxide $Ti _{x}O _{y}$. If $1.6\ gm$ of  $TiO _{2}$ produces $1.44\ gm$ of $Ti _{x}O _{y}$, the formula of new oxide is
[Atomic weight of $Ti=48$]:

  1. $TiO$
  2. $Ti _{2}O _{3}$
  3. $Ti _{2}O _{5}$
  4. $None\ of\ these$
Reveal answer Fill a bubble to check yourself
A Correct answer