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 d- and f-block elements some important compounds of transition elements general properties of transition metals the d-and f-block elements
Mass (g)
Empty crucible $22.01$
Crucible and copper oxide $42.01$
Crucible and copper product $(1^{st}mass)$ $39.87$
Crucible and copper product $(2^{nd}mass)$ $38.01$
Crucible and copper product $(3^{rd}mass)$ $38.01$

Copper ions can have multiple oxidative states. The data table above was obtained during a lab in which an unknown copper oxide was heated in a crucible.
From this data, what is the name of the unknown copper oxide?

  1. Copper(I) oxide.

  2. Copper (II) oxide.

  3. Copper (I) peroxide.

  4. Copper (II) peroxide.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice chemistry d- and f-block elements some important compounds of transition elements general properties of transition metals the d-and f-block elements
State True or False.
Fe$ _3$O$ _4$ is mixed oxide of FeO and Fe$ _2$O$ _3$. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Iron (II,III) oxide is the chemical compound with formula $Fe _3O _4$. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide ($FeO$), which is rare, and iron(III) oxide ($Fe _2O _3$) also known as hematite. $Fe _3O _4$ contains both $Fe^{2+}$ and $Fe^{3+}$ ions and is sometimes formulated as FeO ∙ Fe2O3. 

Multiple choice chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

Gas B is paramagnetic and support the combustion compound B is :

  1. $N _2$
  2. $N _2O$
  3. $O _2$
  4. $Na _2O$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$O _2$ is paramagnetic due to the presence of $2$ unpaired $e^-$ in the $\Pi$-antibonding orbital.

$\sigma1s^2\sigma^*1s^2\sigma2s^2\sigma^*2s^2\sigma2p _3^2\Pi2p _x^2=\Pi2p _y^2\Pi^*2p _x^1=\Pi^*2p _y^1$
Also, $O _2$ supports combustion as it does not burn but it is an oxidizer, it oxidizes other reactive materials, itself getting reduced.

Multiple choice chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

Which compound does nitrogen have oxidation number in fraction?

  1. $NH _{2}OH$
  2. $N _{2}H _{4}$
  3. $NH _{3}$
  4. $N _{3}H$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In hydrazoic acid (N3H), the total oxidation state of the three nitrogen atoms must be -1 to balance the +1 of hydrogen. Thus, the average oxidation state of nitrogen is -1/3, which is a fraction.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

The chemical formula of the oxide of $Eka\ -$ aluminium is:

  1. $GaO$
  2. $GaO _2$
  3. $Ga _2O _2$
  4. $Ge _2O _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Eka$-aluminium is known as $Gallium$.


Gallium forms only two oxides as ${Ga} _{2}O$ or ${Ga} _{2}{O} _{3}$.

It's is in $+1$ and $+3$ oxidation state$.$.

Therefore, the correct option is $D$.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

What type of oxide would Eka-aluminium form?

  1. $EO _3$
  2. $E _3O _2$
  3. $E _2O _3$
  4. $EO$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Eka- Aluminium (E) forms oxide with the same empirical formula is Aluminium oxide. Thus, it forms ${ E } _{ 2 }{ O } _{ 3 }$ oxide.


Hence, option C is correct.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

$0.14\ g$ of an element on combustion gives $0.28\ g$ of its oxide. That is that element?

  1. Nitrogen

  2. Carbon

  3. Fluorine

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

Mass of element = 0.14g, Mass of oxide = 0.28g. Mass of oxygen = 0.28 - 0.14 = 0.14g. Equivalent weight = (Mass of element / Mass of oxygen) * 8. Equivalent weight = (0.14 / 0.14) * 8 = 8. Sulphur has an equivalent weight of 8 (valency 2, atomic mass 32).

Multiple choice chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

In solid state N2O5 exits as:

  1. $[NO3]^ - [NO2]^+$
  2. $[NO2]^ - [NO3]^ +$
  3. $[N2O4]^ + O^-$
  4. $[NO3] [NO2]$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Solid $N _2O _5$ is a salt, consisting of separated anions and cations. The cation is the linear nitronium ion $NO _2^+$ and the anion is the planar nitrate $NO _3^−$ ion. Thus, the solid could be called nitronium nitrate. Both nitrogen centers have oxidation state +5.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which of the following statements is not correct?

  1. All the oxides of halogens are powerful oxidants.

  2. The compounds of oxygen and fluorine are not called oxides but fluorides.

  3. Oxygen fluorides form oxoacids.

  4. In oxyhalides, bonds are mainly covalent due to small difference in electronegativity of oxygen and halogens.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxygen florides forms $HF,O _2$ on hydrolysis.

$OF _2 + H _2O\rightarrow O _2 + 2 HF$

$2O _2F _2 + 2H2O\rightarrow O _2 + 4HF$

so oxygen florides do not form forms hypohalous acids.

So the given statement oxygen florides forms oxoacids is wrong.

Hence option C is correct.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

The oxidation state of Chlorine in Bleaching Powder:

  1. -2
    • 1
    • 1

  4. -1 and + 1
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The chemical formula of bleaching powder is $CaOCl _{2}$. Here, calcium is bonded to $Cl^{-}$ ion and $OCl^{-}$ ion respectively.

In $Cl^{-}$ the oxidation state of chlorine is -1 and in $OCl^{-}$ ion the oxidation state of chlorine is +1.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which one of the following anions can undergo both oxidation and reduction?

  1. $Cr _2{O _7}^{2-}$
  2. $N{O _3}^{-}$
  3. $OCl^-$
  4. ${S}^{2-}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$(A)$ In $Cr _2{O _7}^{2-}$, the oxidation state of $Cr$ is $+6$, which is maximum oxidation of $Cr$. It can only lower down its oxidation state. So, it acts only as an oxidising agent.
$(B)$ In $N{O _3}^{-}$, the oxidation state of $N$ is $+5$, which is the maximum oxidation of $N$. It can only lower its oxidation state  and so, it acts only as an oxidising agent.
$(C)$ In $OCl^-$, the oxidation state of $Cl$ is $+1$ and $Cl$ shows oxidation state from $-1$ to $+7$ and so, it can undergo both oxidation and reduction.
$(D)$ In ${S}^{2-}$, the oxidation state of $S$ is $-2$, which is the minimum oxidation state of $S$ and so, it can only increase its oxidation state and hence, it acts only as a reducing agent.

Therefore, $OCl^-$ can undergo both oxidation as well as reduction.