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

Among :   


$a) Na {2}O  \quad  b)MgO \quad c)Al _{2}O _{3}\quad  d)P _{2}O _{5}\quad  e)Cl _{2}O _{7} \quad $  

the most basic, most acidic and amphoteric oxide can be _______.

  1. a,b,c

  2. b,e,c

  3. a,e,c

  4. e,c,a
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metal being electropositive in nature form basic oxide .non metals being electronegative in nature from acidic oxides .


so the extent of acidity and basicity in oxide depends on electropositive and electronegative nature of elements.


most basic oxide: $Na _2O$
most acidic oxide $Cl _2O _7$
amphoteric oxide: $Al _2O _3$

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

Which of the following oxide having ${{\text{O}} _{\text{2}}}^{{\text{ - 2}}}\,\,\,$

  1. ${\text{Na}}{{\text{O}} _{\text{2}}}\,\,\,$
  2. ${\text{Ba}}{{\text{O}} _{\text{2}}}\,\,\,$
  3. ${\text{Rb}}{{\text{O}} _{\text{2}}}\,\,\,$
  4. ${\text{R}}{{\text{O}} _{\text{2}}}\,\,\,$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The superoxide ion is O2(-). RbO2 is rubidium superoxide, which contains the O2(-) ion. BaO2 is a peroxide (O2(2-)), and NaO2 is a superoxide, but RbO2 is the classic example often cited in this context.

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

Match the following,regarding nature of the oxides
Column-I                                               Column-II
a. ${ N } _{ 2 }O$                         $       (i)Basic$

b. $ BaO$                                       $  (ii)Amphoteric $
            
c. $ { As } _{ 2 }{ O } _{ 3 }$            $     (iii)Acidic$

d. $ { Cl } _{ 2 }{ O } _{ 7 }$           $      (iv) Neutral$

  1. a(ii),b(i),c(iii),d(iv)

  2. a(iv),b(i),c(iii),d(ii)

  3. a(iv),b(i),c(ii),d(iii)

  4. a(ii),b(i),c(iv),d(iii)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Matching the oxide types: N2O is a neutral oxide (iv), BaO is a strong basic oxide (i), As2O3 is an amphoteric/weakly acidic oxide (commonly classed as amphoteric or intermediate, matching ii here), and Cl2O7 is a strong acidic oxide (iii). This correctly aligns with option C.

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

Amphoteric oxides are:

  1. $SnO, SnO _2$
  2. $GeO, GeO _2$

  3. both (a) and (b)

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 Amphoteric oxide is one that reacts with both acids and bases to form salt and water. Thus,  SnO and SnO2 react with both HCl (an acid) and NaOH (base) to give salt and water.


GeO and GeO2 are not well characterized. It is amphoteric dissolving in acids to form germanium(II) salts and in alkali to form trihydroxy germanates or germinates and the GeO has not reacted both the acid and base so GeO is not an Amphoteric.

So the correct answer is A

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

Which of the following set contains oxide in the sequence, basic, amphoteric and acidic respectively?

  1. $SO _2,\, P _2O _5,\, CO$
  2. $BaO,\, Al _2O _3,\, SiO _2$
  3. $CaO,\, SiO _2,\, Al _2O _3$
  4. $Al _2O _3.\, CO _2,\, CO$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Generally Group 1 and Group 2 elements form bases called base anhydrides or basic oxides. Basic oxides are the oxides of metals. If soluble in water, they react with water to produce hydroxides. These metallic oxides are known as basic anhydrides. They react with acids to produce salts
E.g.-$BaO$
Acidic oxides are the oxides of non-metals (Groups 14-17) and these acid anhydrides form acids with water.
$SiO _2$
An amphoteric solution is a substance that can chemically react as either acid or base. For example, when $HSO _4^-$ reacts with water it will make both hydroxide and hydronium ions:
$Al _2O _3$
Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

Which of the following set contains only amphoteric oxides?

  1. $ZnO,\, PbO,\, SnO,\,Al _2O _3$
  2. $ZnO,\, BaO,\, SO _2, CO$
  3. $CO,\, PbO,\, BaO _2,\, SO _2$
  4. $P _2O _5,\, N _2O _5,\, CI _2O _7,\, BaO$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An amphoteric solution is a substance that can chemically react with either acid or base. For example, when $HSO _4^-$ reacts with water it will make both hydroxide and hydronium ions. Amphoteric oxides are metallic oxides, which show both basic as well as acidic properties. When they react with an acid, they produce salt and water, showing basic properties. While reacting with alkalies they form salt and water showing acidic properties.  A common example of an amphoteric oxide is aluminium oxide, Zinc Oxide, SnO, PbO.

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

Out of the following oxides, the amphoteric oxide is:

  1. $Fe _2O _3$
  2. $Al _2O _3$
  3. $P _2O _5$
  4. $N _2O$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aluminium reacts with acids and bases. So, it is amphoteric in nature. The oxide of an amphoteric element is called amphoteric oxide. So, $Al _{2}O _{3} $ is an amphoteric oxide.

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

Pick the group which does not contain a neutral oxide.

  1. $NO _2, P _4O _{10}, Al _2O _3, NO$
  2. $MgO, N _2O _5, SO _3, N _2O$
  3. $CO _2, SO _3, CaO, XeO _3$
  4. $CO, SiO _2, SnO _2, Na _2O _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutral oxide are those which do not react with acids as well as bases such as $NO,{ N } _{ 2 }O,CO,{ O } _{ 2 }{ F } _{ 2 }$.

So only option $C$ does not contain neutral oxide.

Multiple choice chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

Which of the following is not correct observation based on Ellingham diagram?

  1. A metal can reduce the oxide of other metal which lies above it in Ellingham diagram
  2. $CO$ is more effective than $C$ as reducing agent below $170^{o}C$
  3. $\Delta G^{o}$ metal oxide is higher than of $CO _{2}$ hence oxidation of metal sulphides to oxides is not favourable

  4. Need for conversion of metal sulphide to metal oxide before reduction can be explained thermodynamically
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As moving down of bottom of diagram metals becomes more reactive oxides will be hard to reduce.A given metal can reduce the oxides of other metal which lies above it in Ellingham diagram.

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

The oxidation state of nitrogen in ammonia molecule is -3.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The oxidation state of nitrogen in ammonia ($NH _3$) molecule is -3.
Let x be the oxidation state of nitrogen in ammonia. The oxidation state of hydrogen is $ \displaystyle +1$ .
$ \displaystyle x + 3 (+1)=0$
$ \displaystyle x+3=0$
$ \displaystyle x=-3$