Class 11th Chemistry – 8 Redox Reactions MCQs

Each atom in an element, in its free or uncombined state bears an oxidation number of ____.

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Each atom in an element, in its free or uncombined state bears an oxidation number of zero. Example, each atom in H2, O2,Cl2, O3, P4, S8, Na, Mg, Al has the oxidation number zero.

Identify the type of the following redox reaction. CH4 + 2O2→CO2 + 2H2O.

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The redox reaction CH4 + 2O2 → CO2 + 2H2O is a combination reaction. Combination reactions occur when two reactants combine to form the products. Examples, C + O2 → CO2, 3Mg + N2 → Mg3N2.

The electrolytic solutions in a Daniel cell are connected by a ____.

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The electrolytic solutions in a Daniel cell are connected by a salt bridge. The salt bridge provides an electric contact between the two electrolytic solutions without allowing them to mix with each other.

The reaction 4Li + O2 → 2Li2O represents ____ process.

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The reaction 4Li + O2 → 2Li2O represents oxidation process. Originally, the term oxidation was used to describe the addition of oxygen to an element or a compound. Because of the presence of dioxygen in the atmosphere (~20%), many elements combine with it. This is the principal reason that they commonly occur on the earth in the form of their oxides.

In a redox reaction, the oxidation half reaction is Cu → Cu+2 + 2 e- and the reduction half reaction is Ag+ + 1 e- → Ag. The balanced ionic equation is ____.

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The balanced ionic equation is Cu + 2 Ag+→ Cu2++2Ag. The two equations do not have the same number of electrons. There are 2 in the copper reaction but only one in the silver reaction. Multiply everything in the silver reaction by 2 and then add the equations together to get the balanced ionic equation.

In the following reaction HNO3 + Cu +H+→NO2+Cu2+ + H2O, the reduction half reaction is ____.

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The reduction half reaction is HNO3 + H+ → NO2 + H2O. The balanced reduction half reaction is HNO3 +H+ + 1 e- → NO2 + H2O, and the oxidation half reaction is Cu → Cu+2 + 2e-. The balanced equation is 2HNO3 + Cu + 2H+ → 2NO2 + Cu2+ + 2H2O. 2HNO3+Cu + 2H+ →2NO2 + Cu2+ + 2H2O

The reaction CH3CHO → CH3CH2OH represents ____ process.

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The reaction CH3CHO → CH3CH2OH represents reduction process. Reduction can be defined in terms of hydrogen transfer, as gain of hydrogen.

The compound where the oxygen atom is assigned an oxidation number of +2 is ____.

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OF2is the compound where the oxygen atom is assigned an oxidation number of +2. Since the oxidation number of the electronegative element fluorine is -1, the oxidation number of oxygen in OF2 is +2. The oxidation number of other options are, O2F2 is+1,KO2 is -1/2 and Na2O2 is -1.

The non-metal displacement redox reactions include _______ displacement and a rarely occurring reaction involving _______ displacement.

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The non-metal displacement redox reactions include hydrogen displacement and a rarely occurring reaction involving oxygen displacement. Example, 2Na+2H2O→2NaOH + H2.

Oxidation number of iodine varies from

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In KI it shows -1 O.S &in IF7 it shows +7 hence O.S of I varies from -1 to +7.

Hydrogen sulphide gas when passed through a colourless solution containing Zn2+ ions, forms ____.

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Hydrogen sulphide gas when passed through a colourless solution containing Zn2+ ions, forms white zinc sulphide. Zinc sulphide is white in colour and can be seen when the solution is made alkaline with ammonia.

In their compounds, all ______ metals have oxidation number of +1, and all ________ metals have an oxidation number of +2.

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In their compounds, all alkali metals have oxidation number of +1, and all alkaline earth metals have an oxidation number of +2. For ions composed of only one atom, the oxidation number is equal to the charge on the ion. Thus, Na+ ion has an oxidation number of +1, Mg2+ ion, +2, Fe3+ ion, +3, Cl- ion, -1, O2- ion, -2; and so on.

Iodide ions are oxidised by ____ions.

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Iodide ions are oxidised by thiosulphate ions. Iodine itself gives an intense blue colour with starch and has a very specific reaction with thiosulphate ions (S2O32-), which too is a redox reaction.

Which quantities are conserved in all oxidation reduction reaction

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Both charge and mass conserves in an oxidation-reduction reaction.

While representing the redox couple, ____form is put before the ____` form.

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While representing the redox couple, oxidized form is put before the reduced form. In a Daniel cell, the redox couples are represented as Zn2+/Zn and Cu2+/Cu.

The oxidation number of hydrogen in LiH, NaH and CaH2 is ____, ____ and ____ respectively.

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The oxidation number of hydrogen in LiH, NaH and CaH2 is +1, +1 and -1 respectively. The oxidation number of hydrogen is +1, except when it is bonded to metals in binary compounds (that is compounds containing two elements).

Complete the following reaction. Cu(s)+2Ag+(aq)→ ____

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The complete reaction is, Cu(s)+2Ag+(aq)→ Cu2+(aq)+2Ag(s). Here, Cu(s) is oxidised to Cu2+(aq) and Ag+ (aq) is reduced to Ag(s). Equilibrium greatly favours the products Cu2+ (aq) and Ag(s).

One of the following has both positive and negative oxidation states

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Cl has O.S. as -1, +1 +3+5 and +7.

The oxidation number of Mn in KMnO4 is

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1+x+4*(-2) =0; x=+7

The reduction reaction in the process Co(s) + Ni2+(aq) → Co2+(aq) + Ni(s)is ____.

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The reduction reaction in the reaction Co(s) + Ni2+(aq) → Co2+(aq) + Ni(s) is Ni2+(aq)+ 2e-→ Ni(s). The oxidation reaction in the above redox reaction is Co(s) → Co2+(aq)+2e-.

The half-reaction that involves loss of electrons is called ____ reaction.

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The half-reaction that involves loss of electrons is called oxidation reaction. Similarly, the half-reactions that involve gain of electrons are called reduction reactions.

____ is not a self indicator.

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Potassium dichromate is not a self indicator. Self indicator is a chemical which takes part in titration and itself indicate the end point of titration. Potassium dichromate requires an indicator for visual end point work. Ceric sulphate, iodine and potassium permanganate are self indicators.

The species undergoing oxidation in the reaction, Fe2O3 + 3CO → 2Fe + 3CO2, is ____.

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The species that undergoes oxidation in the reaction Fe2O3 + 3CO → 2Fe + 3CO2is carbon monoxide.

loss of electron is termed as

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Losing of electron is called oxidation.

The standard electrode potential of hydrogen electrode is ____.

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The standard electrode potential of hydrogen electrode is 0.00 V. Hydrogen's standard electrode potential (E0) is declared to be zero at all temperatures. Potentials of any other electrodes are compared with that of the standard hydrogen electrode at the same temperature.

Zn2+ (aq.) + 2e- → Zn(s) This is

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Zn2++2e-→Zn(s). Here electrons are reducing from Zn2+ to Zn.

The oxidation process is visualised as a ____in electron density.

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The oxidation process is visualised as a decrease in electron density. The oxidation process is visualised as a decrease in electron density, and reduction process as an increase in electron density around the atom(s) involved in the reaction.

The standard electrode potentials of four elements A, B, C and D are -3.05, -1.66, -0.40 and +0.80. The highest chemical reactivity will be exhibited by:

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Standard electrode potential i.e reduction potential of A is minimum (-3.05V) i.e. its oxidation potential is maximum which implies ‘A’ is most reactive chemically.

In acid-base systems, the titration method is used for finding out the ____of one solution against the other using a ____ sensitive indicator.

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In acid-base systems, the titration method is used for finding out the strength of one solution against the other using a pH sensitive indicator. Titration, also known as titrimetry, is a method of quantitative chemical analysis that is used to determine the unknown concentration of a known reactant.

Oxidation state of oxygen in hydrogen peroxide is

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2*1+2x = 0, x= -1

Class 11th Chemistry - 8 Redox Reactions MCQs
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Class 11th Chemistry - 8 Redox Reactions MCQs