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 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.

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
B Correct answer
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.