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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 651. |
In the following redox reactionn, `Cr_(2)O_(7)^(2-) + Fe^(2+) to Fe^(3+) + Cr^(3+)` 1 mole of `Cr_(2)O_(7)^(2-)` oxidises.A. 1 mole of `Fe^(2+)`B. 3 mole of `Fe^(2+)`C. 4 moles `Fe^(2+)`D. 6 moles of `Fe^(2+)` |
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Answer» Correct Answer - D `underset("1 mole")(Cr_(2)O_(7)^(2-)) + underset("6 mole")(6Fe^(2+)) + 14H^(+) to 2Cr^(3+) + 7H_(2)O + 6Fe^(3+)` |
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| 652. |
On combustion of `CH_(4)` to `CO_(2)` and `H_(2)`, the oxidation number of carbon changes by:A. `8`B. ZeroC. `4`D. `3` |
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Answer» Correct Answer - A `C^(4-) rarr C^(4+) + 8e` |
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| 653. |
The incorrect order of decreasing oxidation number of `S` in compound is:A. `H_(2)S_(2)O_(7) gt Na_(2)S_(4)O_(6) gt Na_(2)S_(2)O_(3) gt S_(8)`B. `H_(2)SO_(5) gt H_(2)SO_(3) gt SCl_(2) gt H_(2)S`C. `SO_(3) gt SO_(2) gt H_(2)S gt S_(8)`D. `H_(2)SO_(4) gt SO_(2) gt H_(2)S gt H_(2)S_(2)O_(8)` |
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Answer» Correct Answer - C, D Oxidation number of `S` are `+6, +4, -2, +6` respectively. |
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| 654. |
When zinc metal is added to dilute `H_(2)SO_(4)` solution, hydrogen is evolved. In this zinc undergoesA. ReductionB. OxidationC. DissolutionD. None of the above |
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Answer» Correct Answer - B `Zn rarr Zn^(2+)+2e` |
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| 655. |
Peroxides are basic in nature and they form hydrogen peroxides on treatment with acid. What volume of 0.5 M `H_(2)SO_(4)` solution is required to neutralise a solution containing 7.2 g of `CaO_(2)` ?A. 400 mlB. 300 mlC. 200 mlD. 100 ml |
| Answer» Correct Answer - C | |
| 656. |
In which one of the following changes there are transfer of five electrons?A. `MnO_(4)^(-) to Mn^(2+)`B. `CrO_(4)^(2-) to Cr^(3+)`C. `MnO_(4)^(-) to MnO_(2)`D. `Cr_(2)O_(7)^(2-) to 2Cr^(3+)` |
| Answer» Correct Answer - A | |
| 657. |
oxidation states available for a particular elements are normally more than the valencies A brown complex has the formula: `[Fe(H_(2))(O)_(5)NO]SO_(4)` the oxidation number of iron is: In which of the following pairs there is the maximum difference in the oxidaation state of the elements other than oxygen?A. `NO_(2) and N_(2)O_(4)`B. `P_(2)O_(5) andP_(4)O_(10)`C. `K_(2)mNo_(4)N_(2)O and NO`D. `SO_(2) and SO_(3)` |
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Answer» Correct Answer - D O.N of N in `NO_(2)and N_(2)O_(4)` are +4 (same). O.N of P in `P_(2)O_(5) and P_(4)O_(4) are +5(same)` O.N of N in `N_(2)O is +1 and NO is +2 (difference=1)` O.N of S in `SO_(2) is (+4) and SO_(3)` is (+6)(dfference=2) |
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| 658. |
oxidation states available for a particular elements are normally more than the valencies A brown complex has the formula: `[Fe(H_(2)O_(5))NO]SO_(4)` the oxidation number of iron is: Phosphorus has the oxidation satate of +3 inA. Phosphorus acidB. Orthophosphoric acidC. Hypophorus acidD. Metaphosphoric acid |
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Answer» Correct Answer - A `(a) H_(3)PO_(3)` `(b)H_(3)PO_(4)` `(c )overset(+3)underset(+1)H_(3)PO_(2)` `(d)overset(+4)underset(+5)HPO` |
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| 659. |
The brown ring complex compound of iron is formulated as `[Fe (H_(2)O)_(5) (NO)] SO_(4)`. The oxidation state of iron isA. 1B. 2C. 3D. 0 |
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Answer» Correct Answer - B::C The ligand NO can be neutral or univalent positive. Here it is neutral. Therefore, O.N of Fe in the complex is +2. |
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| 660. |
The `[CrO_(4)^(2-)]` ions are equilibrium for the reaction, `Cr_(2)O_(7)^(2-)+H_(2)Oharr2CrO_(4)^(2-)+2H^(+), "at" pH=4` is:A. `10^(4)[Cr_(2)O_(7)^(2-).K_(c )]^(1//2)`B. `10^(-8)[Cr_(2)O_(7)^(2-)].K_(c )`C. `10^(-4)[Cr_(2)O_(7)^(2-)]^(1//2)`D. `10^(-4)[Cr_(2)O_(7)^(2-)].K_(c _` |
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Answer» Correct Answer - A `K_(c)=([Cr_(2)O_(7)^(2-)]xxK_(c ))/([H^(+)]^(2))=(K_(c )[Cr_(2)O_(7)^(2-)])/((10^(-4))^(2))` `=10^(4)[K_(c )xxCr_(2)O_(7)^(2-)]^(1//2)` |
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| 661. |
In which reaction there is a change in valencyA. `2NO_(2) rarr N_(2)O_(4)`B. `NH_(4)OH rarr NH_(4)^(+) + OH^(-)`C. `2NO_(2)+H_(2)O rarr HNO_(2)+HNO_(3)`D. `CaCO_(3) rarr CaO+CO(2)` |
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Answer» Correct Answer - C `overset(+4)(2NO_(2))+H_(2)O rarr HNO_(2)+overset(+5)(HNO_(3))`. In this reaction oxidation state changes. |
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| 662. |
In which of the following reactions, there is no change in valency ?A. `SO_(2)+2H_(2)S rarr 2H_(2)O+3S`B. `2Na +O_(2) rarr 2Na_(2)O_(2)`C. `Na_(2)O_(2)+H_(2)SO_(4) rarr Na_(2)SO_(4) +H_(2)O_(2)`D. `3KClO_(3) rarr 3KClO_(4)+KCl` |
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Answer» Correct Answer - C (C) is not a redox reaction and hence no change in valency |
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| 663. |
The equivalent mass of potassium permanganate in alkaline medium isA. Molar mass/5B. Molar mass/3C. Molar mass/2D. Molar mass/1 |
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Answer» Correct Answer - D In alkaline medium, `2KMnO_(4)+2KOHrarr2K_(2)MnO_(4)+H_(2)O+O` Ionic equation `MnO_(4)^(-)+e^(-)rarr MnO_(4)^(2-)` `:.` Eq. wt. of `KMnO_(4)` = Molar mass/1. |
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| 664. |
For the reaction, `I^(-)+CIO_(3)^(-)+H_(2)SO_(4)rarrCI^(-)+HSO_(4)^(-)+I_(2)` the correct statement (s) in the balanced equation `is//are`A. stoichiometric coeffiecient of `HSO_(4)^(-)` is 6B. iodide is oxidisedC. suphur is reducedD. `H_(2)O` is one of the products |
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Answer» Correct Answer - A::B::D The oxidation half reaction is: `2I^(-)rarrI_(2)+2e^(-)` The reduction half rection is : `6H^(+)+CIO_(3)^(-)+6E^(-)rarrCI^(-)+3H_(2)O` Multiply eqn.(i) by 3 and add to eqn.(i) `6H^(+)+CIO_(3)^(-)+6e^(-)rarrCI^(-)+3H_(2)O` `6I^(-)rarr3I_(2)+6e^(-)` `(6I^(-)+6H^(+)+CIO_(3)^(-)rarr3I_(2)+3H_(2)O+CI^(-))/((a) "The stoichiometry of" HSO_(4)^(-) is 6` The `H^(+) "ions are provided by" H_(2)SO_(4) "or" HsO_(4)^(-)` ion (b) `I^(-)` ions are oxidisded to `I_(2)` (d) `H_(2)O` is one of the products formed in the redox rection. |
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| 665. |
Which `CI_(2)` is passed through hot `NaOH` solution, oxidation number of CI changes from E238A. `-1 to 0`B. `0 to -1`C. `0 to +5`D. `0 to +7` |
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Answer» Correct Answer - B::C ` 3overset(0)CI_(2)+^NaOHrarr5Naoverset(-1)CI+Naoverset(+5)CIO_(3)+3h_(2)O` |
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| 666. |
Volume of 0.1M ferrous oxalate solution required to react completely with 60ml of 0.1N acidified `KMnO_(4)` solutionA. 30mLB. 20mLC. 150mLD. 10mL |
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Answer» Correct Answer - b |
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| 667. |
Oxidation number of osmium `(Os)` in `OsO_(4)` isA. `+8`B. `+6`C. `+7`D. `+4` |
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Answer» Correct Answer - A `overset(*)(Os)O_(4)` `x+4(-2)=0` `x-8=0` `x=+8` |
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| 668. |
Oxidation is a process which involves .A. loss of an electronegative radicalB. gain of electronsC. gain of an electropositive radicalD. increase in the oxidation number of one of the atoms |
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Answer» Correct Answer - D Oxidation is an increase in oxidation number and corresponds to the loss, or apparent loss, of electrons (called deelectronation). |
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| 669. |
Justify that the reaction : `2 Na(s) + H_(2)(g) to 2 NaH (s)` is a redox change . |
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Answer» Since in the above reaction the compound formed is an ionic compound , which may also be represented as `Na^(+) H^(-)` (s) , this suggests that one half reaction in this process is : `2 Na(s) to 2 Na^(+) (g) + 2 e^(-)` and the other half reaction is : `H_(2)g + 2 e^(-) to 2 H^(-) (g)` This splitting of the reaction under examination into two half reactions automatically reveals that here sodium is oxidised and hydrogen is reduced , therefore , the complete reaction is a redox change . |
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| 670. |
The oxidation number of nitrogen in nitride ion isA. `+3`B. `-3`C. ` -5`D. ` +5` |
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Answer» Correct Answer - B Nitride ion is `N^(3-)`. For ions composed of only one atom, the oxidation number is equal to the charge on the ion. |
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| 671. |
A redox reaction is:A. Proton transfer reactionB. Neutron transferC. Double displacementD. Electron transfer reaction |
| Answer» Correct Answer - D | |
| 672. |
`SO_(2)` under atomspheric condition changes to `SO_(x)^(2-)`. If oxidation number of `S` in `SO_(x)^(2-)` is `+6`, what is the value of `x` in `SO_(x)^(2-)`?A. `2`B. `1`C. `3`D. `4` |
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Answer» Correct Answer - A `SO_(x)^(2-)rarr6-2x=-2` `:. 2x=8` `x=4` |
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| 673. |
Assertion (A): Sodium perxenate `(Na_(4)XeO_(6))` reacts with `NaF` in acidic medium to give `XeO_(3)` and `F_(2)` Reason (R ): `XeO_(6)^(4-)` is a stronger oxidant than `F_(2)`.A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.B. If both `(A)` and `(R )` are correct but `(R )` is not the correct explanation of `(A)`.C. If `(A)` is correct but `(R )` is incorrect.D. If `(A)` and `(R )` are incorrect. |
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Answer» Correct Answer - A Assertion: `overset(+8)XeO_(6)^(4-)+overset(-1)(2F^(ө))+6H^(o+)rarroverset(+6)(Xe)O_(3)+overset(0)F_(2)+3H_(2)O` Reason: The oxidation number of `Xe` decreases from `+8 "to" +6` in `XeO_(3)` while that of `F` increase from `-1` to zero. Therefore, `XeO_(6)^(4-)` is a stronger oxidant than `F_(2)`. |
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| 674. |
In which of the following is the highest oxidation state not possible?A. `[XeO_(6)]^(4-)`B. `XeF_(8)`C. `OSO_(4)`D. `RuO_(4)` |
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Answer» Correct Answer - B `Xe` shows `+8` oxidation state in `XeF_(6)`, but it does not exist because of steric hindrance of `8 F` atoms. |
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| 675. |
The oxidation number of `I` in `HIO_(4)` isA. `+7`B. `+6`C. `+3`D. `+14` |
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Answer» Correct Answer - A `HIO_(4)`,`(+1)+x+4(-2)=0` ` implies x=+7` |
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| 676. |
Which of the following reactions does not involve either oxidation or reduction ?A. `VO_(2)^(+) rarr V_(2)O_(3)`B. `Na rarr Na^(+)`C. `CrO_(4)^(2-) rarr Cr_(2)O_(7)^(2-)`D. `Zn^(2+) rarr Zn` |
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Answer» Correct Answer - C `{:(overset(**)(C)rO_(4)^(2-),,overset(**)(C)r_(2)O_(7)^(2-)),(x+[(-2)xx4]=2,,2x+(-2)xx7=-2),(x=8-2=+6,,2x=14-2=12),(,,x=12/2=+6):}` In this reaction oxidation and reduction are not involved because there is no change in oxidation number. |
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| 677. |
During the disproportionation of `I_(2)` to iodide and iodate ions, the ratio of iodate and iodide ions formed in alkaline medium isA. `1:5`B. `5:1`C. `3:1`D. `1:3` |
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Answer» Correct Answer - a |
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| 678. |
Oxidation is de-electronation whereas reduction is electronation. Oxidants are the substances which oxidise others and reduced themselves. On the other hand reductants are the substances which reduce others and oxidised themselves. The oxidation number of an element in a compound decides its nature to act as oxidant or reductant. Oxidation-reduction occur simultaneously and the overal chemical change is called redox reaction. Redox reactions are of three types : (i) Intermolecular erdox reactions, (ii) Auto-redox or disproportionation reaction, and (iii) Intramolecular redox reactions. Which of the following shows auto-redox change ? (I) `2HCHO+NaOH rarr HCOONa + H_(2)O` (II) `Cl_(2) + H_(2)O rarr HCl + HClO` (III) `2Cu^(+) rarr Cu^(2+) + Cu` (IV) `Cr+3H_(2)O+3OCl^(-) rarr 3Cl^(-) + 6OH^(-)`A. I,II,IIIB. I,IVC. II, IVD. II, III |
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Answer» Correct Answer - A It involves oxidation of one molecule on the cost of other. |
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| 679. |
Find the of oxidation of Co in `Ag[Co(CO)_(4)]`A. 1B. -1C. ZeroD. None of these |
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Answer» Correct Answer - b |
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| 680. |
In the conversion `NH_(2)OH rarr N_(2)O`, the equivalent weight of `NH_(2)OH` will be:A. `(M)/(4)`B. `(M)/(2)`C. `(M)/(5)`D. `(M)/(1)` |
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Answer» Correct Answer - b |
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| 681. |
Which of the following relations is incorrect for solutions?A. `3N Al_(2)(SO_(4))_(3)=0.5MAl_(2)(SO_(4))_(3)`B. `3MH_(2)SO_(4)=6NH_(2)SO_(4)`C. `1MH_(3)PO_(4)=1//3NH_(3)PO_(4)`D. `1MAl_(2)(SO_(4))_(3)+6NAl_(2)(SO_(4))_(3)` |
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Answer» Correct Answer - c |
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| 682. |
How many litres of a `0.5 N` solution of an oxidising agent are reduced by `2` litres of a `2.0 N` solution of a reducing agent?A. `8`B. `4`C. `6`D. `7` |
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Answer» Correct Answer - A Eq. of `OA=` Eq. of `RA` `implies N_(1)xxV_(1)=N_(2)xxV_(2)` `implies 0.5xxV=2xx2` `implies V=8L` |
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| 683. |
In which pair of substances do the nitrogen atoms have the same oxidation state ?A. `HNO_(3)` and `N_(2)O_(5)`B. `NO` and `HNO_(2)`C. `N_(2)` and `N_(2)O`D. `HNO_(2)` and `HNO_(3)` |
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Answer» Correct Answer - a |
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| 684. |
The oxidation numbers of `Fe` and `S` in iron pyrites areA. `3`, `-1`B. `2`, `-1`C. `3`, `-1.5`D. `4`, `-2` |
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Answer» Correct Answer - D `{:(overset(**)(F)eS_(2),,Feoverset(**)(S)_(2)),(x-4=0,,4+2x=0),(x=+4,,2x=-4),(x=(-4)/2=-2,,):}` |
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| 685. |
In which of the following cpmpounds the oxidation number of carbon is maximumA. `HCHO`B. `CH_(3)OH`C. `CHCl_(3)`D. `C_(12)H_(22)O_(11)` |
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Answer» Correct Answer - C Oxidation number of `C` in `HCHO=0` `CH_(3)OH=-2` `CHCl_(3)=+2` `C_(12)H_(22)O_(11)=0` |
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| 686. |
Oxidation is de-electronation whereas reduction is electronation. Oxidants are the substances which oxidise others and reduced themselves. On the other hand reductants are the substances which reduce others and oxidised themselves. The oxidation number of an element in a compound decides its nature to act as oxidant or reductant. Oxidation-reduction occur simultaneously and the overal chemical change is called redox reaction. Redox reactions are of three types : (i) Intermolecular erdox reactions, (ii) Auto-redox or disproportionation reaction, and (iii) Intramolecular redox reactions. Which of the following show intramolecular redox change? (I) `2KClO_(3) rarr 2KCl+3O_(2)` (II) `(NH_(4))_(2)Cr_(2)O_(7) rarr N_(2)+Cr_(2)O_(3)+4H_(2)O` (III) `NH_(4)NO_(2) rarr N_(2)+2H_(2)O` (IV) `2Cu^(+) rarr Cu^(2+)+Cu`A. I,II,IIIB. I,IVC. II,IIID. II,IV |
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Answer» Correct Answer - A It involves redox change of two species in a molecule. |
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| 687. |
`0.3 g` of an oxalate salts was dissolved in `100 mL` solution. The solution required `90 mL` of `N//20 KMnO_(4)` for complete oxidation. The `%` of oxalate ion in salt is:A. `33%`B. `66%`C. `70%`D. `40%` |
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Answer» Correct Answer - B `"Meq. of oxalate" = "Meq. Of" KMnO_(4)` `(w)/(88/2) xx 1000 = 90 xx (1)/(20)` `:. w_("oxalate") = 0.198 g` `% "oxalate " = (0.198)/(0.3) xx 100 = 66%` |
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| 688. |
`0.3 g` of an oxalate salts was dissolved in `100 mL` solution. The solution required `90 mL` of `N//20 KMnO_(4)` for complete oxidation. The `%` of oxalate ion in salt is:A. `3.3%`B. `66%`C. `70%`D. `40%` |
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Answer» Correct Answer - B Meq. Of `KMnO_(4)=M` eq. of `C_(2)O_(4)^(-2)` `90xx(1)/(2)=100xxN_(C_(2)O_(4)^(2-))` Mmole of oxalate `=(9)/(2xx2)=(9)/(4)` Weight of oxalate `=(9)/(4)xx88xx10^(-3)=22xx9xx10^(-3)` `198xx10^(-3)` `%C_(2)O_(4)^(-2)=(.198)/(.300)xx100=66%` |
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| 689. |
Statement -1. `HCIO_(4)` is a stronger oxidising agent than `HCIO_(3)`. Statement-2. Oxidation state of CI in `HCIO_(4)` is +7 and in `HCIO_(3)`, it is +5. |
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Answer» Correct Answer - B Correct explanation.`(HCIO_(4)=+7) "undergoes decreaser in O.S while changing of" HCIO_(3) (O.S of CI=+5)` |
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| 690. |
Number of moles of electorns in the reaction during formation of 1 mole of `Fe_3O_4` according to the reaction `Fe+H_2OtoFe_3O_4+H_2` will be :A. 1B. 5C. 3D. 8 |
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Answer» Correct Answer - d |
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| 691. |
`0.3 g` of an oxalate salts was dissolved in `100 mL` solution. The solution required `90 mL` of `N//20 KMnO_(4)` for complete oxidation. The `%` of oxalate ion in salt is:A. 0.33B. 0.66C. 0.7D. 0.4 |
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Answer» Correct Answer - b |
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| 692. |
Which equation represents an oxidation-reduction reaction?A. `H_(2)SO_(4)+2NH_(3)rarr(NH_(4))_(2)SO_(4)`B. `H_(2)SO_(4)+Na_(2)CO_(3)rarrNa_(2)SO_(4)+H_(2)O+CO_(2)`C. `2K_(2)CrO_(4)+H_(2)SO_(4)rarrK_(2)Cr_(2)O_(7)+K_(2)SO_(4)+H_(2)O`D. `2H_(2)SO_(4)+CurarrCuSO_(4)+2H_(2)O+SO_(2)` |
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Answer» Correct Answer - d |
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| 693. |
All of the reaction below represent oxidation-reduction processes except the : sA. combustion of tin n chlorine gas.B. decomposition of potasssium chlorate.C. neutralization of sodium hydrochloric acid.D. reaction of magnesium with hydrochloric atoms. |
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Answer» Correct Answer - c |
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| 694. |
A solution of 0.4 g sample of `H_(2)O_(2)` reacted with 0.632 g of `KMnO_(4)` in presence of sulphuric acid. The percentage purity of the sample of `H_(2)O_(2)` is :A. 0.95B. 0.85C. 0.8D. none of these |
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Answer» Correct Answer - b |
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| 695. |
Which change represents an oxidation ?A. `NO_(2)^(-)rarrN_(2)`B. `VO^(2+)rarrVO_(3)^(-)`C. `CIO^(-)rarrCl^(-)`D. `CrO_(4)^(2-)rarrCr_(2)O_(7)^(2-)` |
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Answer» Correct Answer - b |
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| 696. |
What is the oxidation number of `Mo` in `MoO_(2)Cl_(2)` ? |
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Answer» Correct Answer - d |
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| 697. |
Which of the following is not a redox reaction ?A. `CO+NO_(2)rarrCO_(2)+NO`B. `3SnCl_(2)+6HCl+2NOrarr3SnCl_(4)+2NH_(2)OH`C. `PCl_(3)+Cl_(2)rarrPCl_(5)`D. `SiO_(2)+4HFrarrSiF_(4)+2H_(2)O` |
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Answer» Correct Answer - d |
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| 698. |
What is the correct relation between normality (N) and molarity (M) of `K_(2)Cr_(2)O_(7)` acting as oxidising agent in acidic medium?A. M=6NB. N=3MC. M=3ND. |
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Answer» Correct Answer - a |
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| 699. |
What would be the normality of a 0.1 M `K_(2)Cr_(2)O_(7)` solution used as a oxidizing agent of Pb^(2+)?A. 0.1NB. 0.6NC. 0.4ND. 0.2N |
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Answer» Correct Answer - b |
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| 700. |
`C_(2)H_(6)(g)+nO_(2) rarr CO_(2)(g)+H_(2)O(l)` In this equation, the ratio of the coefficients of `CO_(2)` and `H_(2)O` isA. `1 : 1`B. `2 : 3`C. `3 : 2`D. `1 : 3` |
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Answer» Correct Answer - B The balanced equation is `2C_(2)H_(6)+7O_(2) rarr 4CO_(2)+6H_(2)O`. Ratio of the coefficients of `CO_(2)` and `H_(2)O` is `4 : 6` or `2: 3`. |
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