NEET Questions Solved


A compound contains atoms of three elements A,B and C. If the oxidation number of A is +2, Bis +5 and that of C is -2, the possible formula of the compound is

(a) A2(BC3)2

(b) A3(BC4)2

(c) A3(B4C)2

(d) ABC2 

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(b) In A3(BC4)2

3 X oxidation number of A + 2[oxidation number of B + 4 X oxidation number of C] = 0

3 X (+2) + 2[5+4X(-2)] =0

                       6+2[-3] = 0

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Which of the following is a redox reaction?

(a) NaCl + KNO3 NaNO3 + KCl

(b) CaC2O4 + 2HCl CaCl2 + H2C2O4

(c) Mg(OH)2 + 2NH4Cl MgCl2 + 2NH4OH

(d) Zn + 2AgCN 2Ag + Zn(CN)2

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(d) Zn is oxidised and Ag is reduced.

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Which combination is odd with respect to oxidation numbers of S, Cr, N and H respectively:\

(a) H2SO5, H2S2O8, H2SO4, SF6

(b) K2Cr2O7, K2CrO4, CrO5, CrO2Cl2

(c) NH3 , NH4, N3H, NO2-   

(d) CaH2 , NaH , LiH, MgH2

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(c) N in  NH3 , NH4, N3H and  NO2-  has -3, -3, -1/3 and +3 oxidation number respectively.

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Which metal exhibits more than one oxidation states?

(a) Na

(b) Mg

(c) Al

(d) Fe

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(d) +2 and +3

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In the aluminothermic process, aluminium acts as:

(a) an oxidising agent

(b) a flux

(c) a reducing agent

(d) a solder

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(c) Cr2O3 + 2AI Al2O3 + 2Cr

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Which of the following change represents a disproportionation reaction(s)?

(a) Cl2 + 2OH- ClO- + Cl- + H2O

(b) Cu2O + 2H+ Cu2+ + H2O

(c) 2HCuCl2 waterDilution with Cu + Cu2+ + 4 Cl- +  2H+

(d) All of the above

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(d) The same species in each reaction is oxidised and reduced well to give disproportionation reaction.

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During a redox change, the oxidant K2Cr2O7 is always reduced to:

(a) Cr5+

(b) Cr4+

(c) Cr3+

(d) Cr2+

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(c) Cr26+ + 6e  2Cr3+

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The reaction, 

3ClO-(aq)ClO3-(aq) + 2Cl-(aq)

is an example of:

(a) oxidation reaction

(b) reduction reaction

(c) disproportionation reaction

(d) decomposition reaction

 

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(c) Cl atom is oxidised (Cl1+Cl5+ +4e) as well as Cl atom is reduced (Cl1+ + 2eCl-) Such reactions are called auto redox or disproportionation reactions.

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Which is not a redox change?

(a) CaCO3 CaO + CO2

(b) 2H2 + O2 2H2O

(c) Na + H2 NaOH + 1/2 H2

(d) MnCl3  MnCl2 + 1/2 Cl2

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(a) No change in oxidation no. in any of the species.

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If H2S is passed through an acidified K2Cr2O7 solution, the colour of the solution:

(a) will remain unchanged

(b) will change to deep red

(c) will change to dark green

(d) will change to dark brown 

Concept Videos :-

#1 | Oxidation Number

Concept Questions :-

Introduction to Redox

(c) Cr3+ ion is green; Cr26+ + 6e 2Cr3+

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