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

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

$Pb{O} _{2}$ 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

Which of the following oxide is least basic?

  1. $CrO$
  2. $Cr _2O _3$
  3. $CrO _3$
  4. $Cr _2O _4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As the oxidation state of a metal increases, its metallic character decreases and the covalent character of its oxide increases, leading to more acidic behavior. In CrO3, chromium is in the +6 oxidation state, making it acidic rather than basic, and thus it is the least basic among the choices.

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
B Correct answer
Explanation

Using mass conservation, moles of Ti in 1.6 g of TiO2 can be calculated. By finding the mass of oxygen removed during reduction by hydrogen, we determine the empirical formula of the resulting titanium oxide to be Ti2O3.

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

The pair of amphoteric oxides is: 

  1. $VO,\,C{r _2}{O _3}$
  2. ${V _2}{O _5},\,C{r _2}{O _3}$
  3. $V{O _2},\,C{r _2}{O _3}$
  4. ${V _2}{O _5},\,Cr{O _3}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
An amphoteric compound is a molecule or ion that can react both as an acid and as a base. Many metals (such as copper, zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. 

Amphoterism depends on the oxidation states of the oxide. Al2O3 is an example of an amphoteric oxide.

 V2O5 and Cr2O3 are amphoteric oxides because both react with alkalies as well as acids.

So, option B is correct
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following oxide is most acidic? 

  1. $Na _2O$
  2. $MgO$
  3. $SiO _2$
  4. $Cl _2O _7$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Na _2O$ , MgO are basic oxides.

$Cl _2O _7$  has highest acidity because it is an oxide of non metal .
Non metallic oxides are acidic 
This oxide reacts with water to give $HClO _4$ i,e,. strong acid.
So, 

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

Which of the following oxides is neutral?

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

Carbon monoxide (CO) does not react with acids or bases to form salts under normal conditions, classifying it as a neutral oxide. In contrast, SnO2 and ZnO are amphoteric, and SO2 is acidic.

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

An element $X$ which occurs in the second period has an outer electronic structure $s^{2}p^{2}$. The formula and acid-base character of its oxide, respectively are,

  1. $XO _{3}$, basic
  2. $X _{2}O _{3}$, basic
  3. $X _{2}O _{3}$, amphoteric
  4. $XO _{2}$, acidic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The outer electronic configuration given is $ns^2np^2$. It is the configuration of the Carbon family. So we know that non-metal oxides are acidic and have general formula $XO _2$.
Option D is correct.
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the oxide gives two oxyacid in water ?

  1. ${N _2}{O _3}$
  2. $NO$
  3. $N{O _2}$
  4. ${P _4}{O _{10}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxyacid, any oxygen-containing acid. Most covalent nonmetallic oxides react with water to form acidic oxides; that is, they react with water to form oxyacids that yield hydronium ions (H3O+) in solution. There are some exceptions, such as carbon dioxide, CO, nitrous oxide, N2O, and nitric oxide, NO.