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 substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

The average oxidation state of chlorine in bleaching power is :

  1. -1

  2. +1

  3. zero

  4. -2 as well as +2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In bleaching powder, $Ca(OCl)Cl$, the two $Cl$ atoms are in different oxidation states i.e., one $Cl^–$ having oxidation number of –1 and the other as $OCl^–$ having oxidation number of +1.


Hence, the average oxidation state of chlorine in bleaching powder is zero.

Multiple choice chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

Oxidation number of $Cl$ in ${ CaOCl } _{ 2 }$ (bleaching powder) is:

  1. zero, since it contains ${ Cl } _{ 2 }$
  2. $-1$, since it contains ${ Cl }^{ - }$
  3. $-1$, since it contains ${ ClO }^{ - }$
  4. $+1$ and $-1$ since it contains ${ ClO }^{ - }$ and ${ Cl }^{ - }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
In bleaching powder,$CaOCl _2,$ the two $Cl$ atoms are in different oxidation states i.e.,one $Cl$ atom having oxidation number of $-1$ and the other as $OCl^-$ having oxidation number of $+1$.
Therefore,$+1$ and $-1$ Since it contains $ClO^-$ and $Cl^-$
Ans is option $D$
Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

The standard reduction potentials of $Pt|Cr {2}O _{7}^{2-}, Cr^{+3}; Pt|MnO _{4}^{-}, Mn^{+2}; Pt|Ce^{+4}, Ce^{+3}$ in the presence of acid are 1.33 V, 1.51 V and 1.61 V, respectively, at $25^{\circ}C$. The decreasing order of oxidizing power is _________________.

  1. $Cr _{2}O _{7}^{2-} > MnO _{4}^{-} > Ce^{+4}$
  2. $MnO _{4}^{-}> Cr _{2}O _{7}^{2-} > Ce^{+4}$
  3. $Ce^{+4} > MnO _{4}^{-}> Cr _{2}O _{7}^{2-}$
  4. $MnO _{4}^{-} > Ce^{+4} > Cr _{2}O _{7}^{2-}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxidizing power is directly proportional to the standard reduction potential. The values are Ce4+ (1.61 V) > MnO4- (1.51 V) > Cr2O7 2- (1.33 V).

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Which of the following compounds on thermal decomposition yields a basic as well as an acidic oxide?

  1. $KClO _3$
  2. $NaNO _3$
  3. $K _2CO _3$
  4. $MgCO _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$MgCO _3\xrightarrow{\Delta} MgO+CO _2$

Since oxides of metals are basic in nature, $MgO$ is basic, and $CO _2$ is acidic. Hence decoposition of $MgCO _3$ yields both acidic and basic oxides

Multiple choice chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

In which of the following, oxidation number of chlorine is $ + 5 ?$

  1. $Cl _{2}O _{7}$
  2. $\mathrm { ClO } _ { 3 } ^ { - }$
  3. $\mathrm { CHO } ^ { - }$
  4. $\mathrm { ClO } _ { 4 } ^ { - }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxidation number of $Cl _2O _7$:-

   $2x-14=0$
$x=7$

Oxidation number of ${ClO _3}^{-}$:-
$x-6=-1$
$x=5$
Oxidation number of $ClO^-$:-
$x-2=-1$
$x=1$
Oxidation number of ${ClO _4}^-$:-

$x-8=-1$
$x=7$
hence option B is correct.

Multiple choice chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

The halogen $($Group $17$ elements$)$:

  1. have an electron configuration of a noble gas less seven electrons

  2. are highly electro positive
  3. show variable oxidation state of $-1, +1, +3, +5$ and $+7$ in their various compounds
  4. forms a volatile, covalent hydrides $HX$ in which the halogen $(X)$ shows an oxidation state of $+1$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fluorine is the most electronegative in halogen family so it has oxidation number of -1 in all its compounds but Cl,Br and I are less electronegative so these elements prepare compounds with oxidation number of +1,+3,+5 and +7.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Different proportions of oxygen in the various oxides of nitrogen proves the law of:

  1. equivalent proportions

  2. conservation of mass

  3. multiple proportions

  4. constant proportions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The existence of multiple oxides of nitrogen (like NO, NO2, N2O) where different masses of oxygen combine with a fixed mass of nitrogen is the definition of the law of multiple proportions.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

An elements forms two oxides containing respectively 53.33 and 36.36 percent of oxygen. These figures illustrate the law of :

  1. Conservation of mass

  2. Constant proportions

  3. Reciprocal proportions

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

An element forms to oxides containing different percentages of oxygen this illustrates that a fixed mass of the elements combine to give more than one compound then they would do so in a simple whole number ratio. Hence this illustrates law of multiple proportions.