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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.
| 1051. |
__`Sn^(2+)`(aq)+__`NO_(3)^(-)`(aq)+__`H^(+)`(aq)`rarr`__`Sn^(4+)` (aq) +__`NO(g)+` __`H_(2)O` What is the coefficent for `H^(+)` (aq) when the equation above is balanced correctly with the smallesr interger coefficients?A. 2B. 4C. 6D. 8 |
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Answer» Correct Answer - d |
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| 1052. |
Balance the following equations by oxidation number method: a. `Fe^(2+) + Sn^(+2) rarr Sn^(4+) + fe^(2+)` b. `MnO_(4)^(Ө) + H_(2)S rarr S+Mn^(2+)` c. `Cr_(2)O_(7)^(2-) + 2I^(Ө) rarr 2Cr^(3+) + I_(2)` d. `Zn + NO_(3)^(Ө) rarr Zn^(2+) + NH_(4)^(o+)` e. `MnO_(4)^(Ө)+SO_(3)^(2-) rarr SO_(4)^(2-)+MnO_(2)` f. `Cl_(2)+IO_(3)^(Ө) rarr IO_(4)^(Ө)` (in basic medium) |
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Answer» Correct Answer - A a. `2Fe^(3+)+Sn^(2+)rarrSn^(4+)+2Fe^(2+)` b. `2MnO_(4)^(ө)+5H_(2)S+6H^(o+)rarr2Mn^(2+)+5S+8H_(2)O` c. `14H^(o+)+Cr_(2)O_(7)^(2-)_6I^(ө)rarr2Cr^(3)+3I_(2)+7H_(2)O` d. `10H^(o+)+4Zn+NO_(3)^(ө)rarr4Zn^(2+)+NH_(4)^(o+)+3H_(2)O` e. `2H^(o+)+2MnO_(4)^(ө)+3SO_(3)^(2-)rarr2MnO_(2)+3SO_(4)^(2-)+H_(2)O` f. `Cl_(2)+IO_(3)^(ө)+2overset(ө)OHrarr2Cl^(ө)+IO_(4)^(ө)+H_(2)O` |
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| 1053. |
__`Sn^(2+)`(aq)+__`MnO_(4)^(-)`(aq)+__`H^(+)`(aq)`rarr`__`Sn^(4+)` (aq) +__`MnO^(2+)`(aq) __`H_(2)O(l)` When this equation for the reaction of `Sn^(2+)` (aq) and `MnO_(4)^(-)` (aq) is balanced correctly, what is the ratio, `Sn^(2+)//MnO_(4)^(-)` ?A. `(1)/(1)`B. `(1)/(2)`C. `(2)/(1)`D. `(5)/(2)` |
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Answer» Correct Answer - d |
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| 1054. |
What is the atomic mass of a metal whose specific heat capaity `(1)/(9)` cal/`gm^(@)`C and whose percentage by mass in its superoxide is 36%?A. 57.6B. 54C. 36D. 64 |
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Answer» Correct Answer - a |
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| 1055. |
Oxidation state of oxygen atom in potassium superoxide isA. `0`B. `-(1)/(2)`C. `-1`D. `-2` |
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Answer» Correct Answer - B In potassium superoxide `(KO_(2))` oxygen shows `-(1)/(2)` oxidation state. |
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| 1056. |
The oxidation number and covalency of sulphur in the sulphur molecule `(S_(8))` are respectively:A. `0` and `2`B. `+6` and `8`C. `0` and `8`D. `+6` and `2` |
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Answer» Correct Answer - A Oxidation number in elemental form is zero. Covalency is two because of `s-s-s-s-` chain. |
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| 1057. |
Point out the oxidation number of `C` in the following: `CH_(4),C_(3)H_(8),C_(2)H_(6),C_(4)H_(10),CO,CO_(2)` and `HCO_(3)^(-),CO_(3)^(2-)` |
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Answer» `CH_(4): -4, C_(3)H_(8):-(8)/(3), C_(2)H_(6):-3` `C_(4)H_(10):-(10)/(4), CO:+2 , CO_(2):+4`, `HCO_(3)^(-):+4, CO_(3)^(2-):+4` |
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| 1058. |
Which of the following has//have been arranged in order of decreasing oxidation number of sulphur?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. `SO^(2+) gt SO_(4)^(2-) gt SO_(3)^(2-) gt HSO_(4)^(ө)`C. `H_(2)SO_(5) gt H_(2)SO_(3) gt SCl_(2) gt H_(2)S`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 - A::C `{:(H_(2)S_(2)O_(7):,2+2x-14=0implies,x=6,,),(Na_(2)S_(4)O_(6):,2+4x-12=0implies,x=2.5,,),(Na_(2)S_(2)O_(3):,2+2x-6=0implies,x=2,,),(,S_(8):8x=0impliesx=0,,,):}]underset("state if S")("Oxidation")` c. `H_(2)SO_(5)` (Peroxo linkage) Oxidation state of `S= +6` `H_(2)SO_(3): 2+x-6=0` Oxidation state of `S= +4` `SCl_(2):x-2=0` Oxidation state of `S= +2` `H_(2)S:2+x=0` Oxidation state of `S= -2` |
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| 1059. |
Find the oxidation number of carbon in the following compounds: `CH_(3)OH, CH_(2)O, HCOOH, C_(2)H_(2)`. |
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Answer» Let the oxidation number of carbon be `a`. `CH_(3)OH : a+3 xx 1+1xx(-2)+1xx1 = 0 rArr a = -2` `CH_(2)O : a+2xx1+1xx(-2) = 0 rArr a = 0` `HCOOH : 1+a+2xx (-2)+1 = 0 rArr a = +2` `C_(2)H_(2) : 2xxa+2xx1 = 0 rArr a = -1` |
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| 1060. |
1 g of oleum sample is dilute with water. The solution required 54 mL of 0.4 N NaOH for complete neutralization. Find the percentage of free `SO_(3)` in the sample? |
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Answer» Correct Answer - 26 |
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| 1061. |
Oxidation is defined as:A. loss of electronsB. gain of electronsC. gain of protonsD. loss of protons |
| Answer» Correct Answer - A | |
| 1062. |
Oxidation is defined as:A. Gain of electronsB. Decrease in positive valencyC. Loss of electronsD. Decrease in negative valency |
| Answer» Correct Answer - C | |
| 1063. |
Assertion :- Oxidation number of `S` in `HSO_(3)^(-)` is `+4`. Reason :- Sulphur is in different oxidation state in different compounds.A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.C. If Assertion is True but the Reason is False.D. If both Assertion & Reason are False. |
| Answer» Correct Answer - B | |
| 1064. |
Find the oxidation number of sulphur in the following compounds: `H_(2)S,H_(2)SO_(4),S_(2)O_(4)^(2-),S_(2)O_(8)^(2-),HSO_(3)^(ө)`. |
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Answer» Correct Answer - B::C::D For neutral molecule, sum of oxidation number of all the atoms is equal to zero and for a charged species equals to the charge on the ion. In `H_(2)S`, the oxidation number of `H` is `+1`, `H_(2)S=2+x-0` `x= -2` Oxidation number of `S= -2` In `H_(2)SO_(4)`, the oxidation numoer of `H` is `+1`, for `O` it is `H_(2)SO_(4)= 2+x-8= 0` `x=+6` Oxidation number of `S` is `+6`. In `S_(2)O_(4)^(2-)`, oxidation number of `O` is `-2`, `S_(2)O_(4)^(2-): , 2x-8= -2` `x=3` `:.` oxidation numbers of `S` is `+3` In `S_(2)O_(8)^(2-)`, we have one peroxide bond, therefore, for two oxygens atom, oxidation number is `-1` and for the order six oxygen atoms, the oxidation number is `-2`. or oxidation number of `S=6`. In `HSO_(3)^(ө)`, oxidation number for `H` is `+1` and oxidation number of `O` is `-2` `1+`(oxidation number of S) `+3(-2)= -1` or oxidation number of `S= +4` It may be noted that sulphur is in different oxidation number states in different compounds. The is true in the next example also in which `Cl` is in different oxidation state. |
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| 1065. |
The resonating structures of cyanate ion are `O=C=overset(1-)(N)harroverset(1-)(O)-C-=Nharroverset(1+)-=C-overset(2-)(N)` . The correct set of oxidation states of O, C and N respectively with the most stable structure out of the above is :A. `-2,+4,3`B. `-2,+4,-3`C. `2,+4,-3`D. `0,+4,-5` |
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Answer» Correct Answer - b |
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| 1066. |
Which of the following is not an intermolecular redox reaction?A. `MgCO_(3) rarr MgO + CO_(2)`B. `O_(2) + 3H_(2) rarr 2H_(3)O^(+)`C. `K + H_(2)O rarr KOH + ((1)/(2))H_(2)`D. `MnBr_(3) rarr MnBr_(2) + ((1)/(2)) Br_(2)` |
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Answer» Correct Answer - A Intermolecular redox reactions and redox reactions are same. `overset(+2)(M)g overset(+4)(C) overset(-2)(O_(3)) rarr overset(+2)(M)g overset(-2)(O) + overset(+4)(C) overset(-2)(O_(2))` As there is no change in oxidation number of atoms, therefore, this reaction is not an intermolecular redox reaction. |
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| 1067. |
[Which of the following is not an intermolecular redox reaction?A. `MgCO_(3)rarrMgO+CO_(2)`B. `O_(2)+2H_(2)rarr2H_(2)O`C. `K+H_(2)OrarrKOH+(1//2)H_(2)`D. `MnBr_(3)rarrMnBr_(2)+(1//2)Br_(2)` |
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Answer» Correct Answer - A Intermolecular redox reaction and redox reactions are same. |
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| 1068. |
An aqueous solution containing 0.10 g `KIO_(3)` (formula weight`=214.0`) was treated with an excess of KI solution the solution was acidified with HCl. The liberated `I_(2)` consumed 45.0 " mL of " thiosulphate solution to decolourise the blue starch-iodine complex. Calculate the molarity of the sodium thosulphate solution. |
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Answer» We know, `KIO_(3)+5KIrarr3K_(2)O+3I_(2)` i.e, `2I^(5+)+10erarrI_(2)^(0)` `2I^(-)rarrI_(2)^(0)+2e` Now the liberated `I_(2)` reacts with `Na_(2)S_(2)O_(3)` to give `I_(2)+2erarr2I^(-)` `2S_(2)O_(3)^(2-)rarrS_(4)O_(6)^(2-)+2e` `because` Milli-mole ratio is `I_(2):S_(2)O_(3)::1:2` Thus, milli`-`mole of `Na_(2)S_(2)O_(3) "used"xx(1)/(2)` `=45xxMxx(1)/(2)` ( `M` is molarity of thiosulphate) Also milli-mole ratio of `KIO_(3): I_(2)::1:3` Thus, `((0.1)/(214))/((45M)/(2))=(1)/(3)` `therefore M=(0.1xx1000xx3xx3)/(214xx45)=0.062` |
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| 1069. |
An aqueous solution containing 0.10 g `KIO_(3)` (formula weight`=214.0`) was treated with an excess of KI solution the solution was acidified with HCl. The liberated `I_(2)` consumed 45.0 " mL of " thiosulphate solution to decolourise the blue starch-iodine complex. Calculate the molarity of the sodium thosulphate solution.A. 0.0623MB. 0.0313MC. 0.126MD. 0.252M |
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Answer» Correct Answer - a |
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| 1070. |
The oxidation number of `Cr` in `K_(2)Cr_(2)O_(7)` isA. `+2`B. `+4`C. `+6`D. `+7` |
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Answer» Correct Answer - B Let the oxidation number of Cr in `K_(2)Cr_(2)O_(7)` be x. Oxidation number of `O = -2 , K = +1` `2 xx 1 + 2x + 7(-2)=0` `2x = 12, x=+6` |
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| 1071. |
The equivalent weight of `KIO_(3)` in the reaction `2Cr(OH)_(3)+4OH+KIO_(3) rarr 2CrO_(4)^(2-)+5H_(2)O+KI` isA. `(Mol.wt.)/(3)`B. `(Mol.wt.)/(6)`C. `(Mol.wt.)/(2)`D. Molecular weight |
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Answer» Correct Answer - A `("Molecular weight")/(3)` Because in `KIO_(3)` effective oxidation number is `3`. |
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| 1072. |
What products are expected from the desproprtionation reactin of hypochorous acid ?A. ` HClO_2` and ` HClO_4`B. ` HClO_3` and ` Cl_2O`C. ` HCl` and ` Cl_2 O`D. ` HCl` and ` HClO_3` |
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Answer» Correct Answer - D The hypohalite ions tend to disproprtionate, particularly in basic solution . The rate of desproportionation reaction increases with temperature: ` 3OX^(-) rarr 2X^(-) + XO_3^(-)` or ` 3HO overset (+1) (CI) rarr 2H overset (-1) (CI) + H overset (+5) (CI)O_3`. |
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| 1073. |
`K_(2)Cr_(2)O_(7)` react with hydrazins to form product. The oxidation state of Cr in the product will be :-A. `+4`B. `+3`C. `+5`D. `+2` |
| Answer» Correct Answer - B | |
| 1074. |
How much amount of `CuSO_(4).5H_(2)O` required for liberation of `2,55gI_(2)` when titrated with KIA. 2.5 gmB. 4.99 gmC. 2.4 gmD. 1.2 gm |
| Answer» Correct Answer - B | |
| 1075. |
In which of the following compounds, nitrogen exhibits the highest oxidation state?A. `N_(3)H`B. `NH_(2)OH`C. `N_(2)H_(4)`D. `NH_(3)` |
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Answer» Correct Answer - A Let the oxidation state of nitrogen in the given compounds be `x`. (`a`) `overset(x)(N_(3))overset(+1)(H) implies (x)3+(+1)=0 implies 3x= -1` `implies x= -(1)/(3)` (`b`) `overset(x)(N)overset(+1)(H_(2))overset(-2+1)(OH) implies x+(+1)2+(-2)+(+1)=0` `x+2-2+1=0 implies x= -1` (`c`) `overset(x)(N_(2))overset(+1)(H_(4)) implies 2(x)+(+1)4=0` `implies 2x= -4 implies x= -2` (`d`) `overset(x)(N)overset(+1)(H_(3)) implies x+(+1)3=0` `x= -3` `:.` Oxidation state of nitrrogen is highest in `N_(3)H`. |
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| 1076. |
What is the oxidation number and valency of carbon in methanal `(HCHO)`? |
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Answer» Correct Answer - D `0,4` |
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| 1077. |
Consider the following reaction : `HCHO+2[Ag(NH_(3))_(2)]^(+)+3OH^(-)rarr2Ag+HCO O^(-)+4NH_(3)+2H_(2)O` Which of the following statements regarding oxidation and reduction is correct?A. HCHO is oxidised to `HCO O^(-)` and `[Ag(NH_(3))_(2)]^(+)` is reduced to Ag.B. HCHO is reduced to `ddHCO O^(-)` and `[Ag(NH_(3))_(2)]^(+)` is oxidised to Ag.C. `[Ag(NH_(3))_(2)]^(+)` is reduced to Ag while `OH^(-)` is oxidised to `HC O O^(-)`D. `[Ag(NH_(3))_(2)]^(+)` is oxidised to `NH_(3)` while HCHO is reduced to `H_(2)O`. |
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Answer» Correct Answer - A `HCHO+2[Ag(NH_(3))_(2)]^(+)+3OH^(-)rarr2Ag+HCO O^(-)+4NH_(3)+2H_(2)O` `HCHO rarr HCO O^(-)` (oxidation) `[Ag(NH_(3))_(2)]^(+)rarr Ag` (reduction) |
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| 1078. |
In which of the following compounds, nitrogen exhibits highest oxidation state ?A. `N_(3)H`B. `NH_(2)OH`C. `N_(2)H_(4)`D. `NH_(3)` |
| Answer» Correct Answer - A | |
| 1079. |
In which of the following compounds,nitrogen exhibits highest oxidation state?A. `N_(2)H_(4)`B. `NH_(3)`C. `N_(3)H`D. `NH_(2)OH` |
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Answer» Correct Answer - C `overset(-2)(N_(2))H_(4),overset(-3)(N)H_(3),overset(-(1)/(3))(N_(3))H,overset(-1)(NH_(4))OH` |
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| 1080. |
In the reaction `:Cl_(2)+OH^(-)rarrCl^(-)+ClO_(4)^(-)+H_(2)O` :-A. Chlorine is oxidisedB. Chlorine is reduced.C. Chlorine is oxidised as well as reduced.D. Chlorine is neither oxidised nor reduced. |
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Answer» Correct Answer - C `Cl_(2)+OH^(-)rarrCl^(-)+ClO_(4)^(-)+H_(2)O` `overset(0)Cl_(2) rarr overset(-1)(Cl^(-)) ` (Reduction) `overset(0)Cl_(2)rarr overset(+7)(Cl)O_(4)^(-)` (Oxidation) |
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| 1081. |
Fluorine reacts with ice and results in the change: `H_(2)O(s)+F_(2)(g) rarr HF(g)+HOF(g)` Justify that this reaction is a redox reaction. |
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Answer» Let us write the oxidation number of each atom involved in the given reaction above its symbol as: `overset(+1)(H_(2)) overset(-2)(O) + overset(0)(F_(2)) to overset(+1)(H) overset(-1)(F) + overset(-1)(H)overset(-2)(O)overset(+1)(F)` Here , we have observed that the oxidation number of F increases from 0 in `F_(2)` to `+1` in HOF . Also, the oxidation number decreases from 0 in `F_(2)` to `–1` in HF. Thus, in the above reaction, F is both oxidized and reduced. Hence, the given reaction is a redox reaction. |
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| 1082. |
In which of the following compounds, carbon exhibits a valency of four but oxidation state of -2 ?A. `CH_(3)Cl`B. `CHCl_(3)`C. `CH_(2)Cl_(2)`D. `HCHO` |
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Answer» Correct Answer - A The valency of C in all the four compounds is 4 but O.N of C in `CH_(3)Cl` is `x + 3 xx 1 + 1(-1) = 0` of x = -2. |
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| 1083. |
In which of the following compounds, an elements exhibits two different oxidation states?A. `NH_(2)OH`B. `NH_(4)NO_(3)`C. `N_(2)H_(4)`D. `N_(3)H` |
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Answer» Correct Answer - b `NH_(4)NO_(3)` is actually `NH_(4)^(+)` and `NO_(3)^(-)`. It is an ionic compound The oxidation number of nitrogen in the two species is different as shown below Let, oxidation number of `N` in `overset(+)(N)H_(4)` is x. `rArr x+(4xx1)=+1` or `x+4=+1` or `x=-3` Let, oxidation number of N in `NO_(3)^(-)` is x `rArr x+(3xx-2)=-1` or `x-6=-1` or `x=+5` |
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| 1084. |
Consider the redox reaction `2S_(2)O_(3)^(2-)+I_(2)rarrS_(4)O_(6)^(2-)+2I^(ө)`A. `S_(2)O_(3)^(2-)` gets reduced to `S_(4)O_(6)^(2-)`B. `S_(2)O_(3)^(2-)` gets oxidised to `S_(4)O_(6)^(2-)`C. `I_(2)` gets reduced to `I^(ө)`D. `I_(2)` gets oxidised to `I^(ө)` |
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Answer» Correct Answer - B::C `2S_(2)O_(3)^(2-)rarrS_(4)O_(6)^(2-)+2e^(-) ("Oxidation")` `I_(2)+2e^(-)rarr2I^(ө)("Reduction")` |
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| 1085. |
Consider the redox reaction `2S_(2)O_(3)^(2-)+I_(2)rarrS_(4)O_(6)^(2-)+2I^(ө)`A. `S_(2)O_(3)^(2-)` gets reduced to `S_(4)O_(6)^(2-)`B. `S_(2)O_(3)^(2-)` gets oxidised to `S_(4)O_(6)^(2-)`C. `I_(2)` gets reduced to `I^(-)`D. `I_(2)` gets oxidised to `I^(-)` |
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Answer» Correct Answer - b,c |
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| 1086. |
The reaction `Cl_(2)(g)+20H^(-)(aq)toClO^(-)(aq)+Cl^(-)(aq)+H_(2)O(l)` represents the process of bleaching. Identify and name the species that bleaches the substances due to its oxidising action. |
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Answer» `overset(0)(Cl_(2))(g)+2overset(-2)(O)overset(+1)(H^(-))(aq)to overset(+1)(Cl)overset(-2)(O^(-))(aq)+overset(-1)(Cl^(-))(aq)+overset(+1)(H_(2))overset(-2)(O)(l)` In this reaction, O.N. of Cl increases from 0 ( in `Cl_(2)`) to 1 (in `ClO^(-)`) as well as decreases from 0 (in `Cl_(2)`) to -1 (in `Cl^(-1)`). So, it acts both reducing as well as oxidising agent. This is an example of disproportionation reaction. In this reaction, `ClO^(-)` species bleaches the substances due to its oxidising action. [In hypochlorite ion `(ClO^(-))Cl` can decrease its oxidation number from +1 to 0 or -1.] |
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| 1087. |
Using the standard electrode potential, find out the pair between which redox reaction is not feasible. `E^(θ)` values: `Fe^(3+)//Fe^(2+)=0.77, I_(2)//I^(-)=+0.54`, `Cu^(2+)//Cu=+0.34, Ag^(+)//Ag=+0.80V`A. `Fe^(3+)` and `I^(-)`B. `Ag^(+)` and `Cu`C. `Fe^(3+)` and `Cu`D. `Ag` and `Fe^(3+)` |
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Answer» Correct Answer - d (a) `2Fe^(3+)+2e^(-)to2Fe^(2+),E^(@)=+0.77V` `2I^(-)toI_(2)+2e^(-), E^(@)=-0.54V" "`(Sign of `E^(@)` is reversed) `2Fe^(3+)+2I^(-)to2Fe^(2+)+I_(2), E_("cell")^(@) = +0.23V` This reaction is feasible since `E_("cell")^(@)` is positive. (b) `CutoCu^(2+)+2e^(-), E^(@)=-0.34V" "`(Sign of `E^(@)` has been reversed) `2Ag^(+)+2e^(-)to2Ag, E^(@)=+0.80V` `Cu+2Ag^(+)to2Cu^(2+)+2Ag, E^(@)=+0.46V` this reaction is feasible since `E_("cell")^(@)` is positive. (c ) `{:(2Fe^(3+)+2e^(-)to2Fe^(2+),E^(@)=+0.77V),(CutoCu^(2+)+2e^(-),E^(@)=-0.34V):}/(2Fe^(3+)+Cuto2Fe^(2+)+Cu^(2+),E^(@)=+0.43V)" "`(sign of `E^(@)` is reversed) This reaction is feasible since `E_("cell")^(@)` is positive. (d) `Ag toAg^(+)+e^(-),E^(@)=-0.80V" "`(sign of `E^(@)` is reversed) `Fe^(3+)+e^(-)toFe^(2+),E^(@)=+0.77V` `Ag+Fe^(3+)toAg^(+)+Fe^(2+),E^(@)=-0.03V` This reaction is not feasible since `E_("cell")^(@)` is negative |
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| 1088. |
The oxidation number of an element in a compound is evaluated on the basis of certain rules. Which of the following rules is not correct in this respect ?A. The oxidation number of hydrogen is always +1B. The algebraic sum of all oxidation numbers in a compound is zeroC. An element in the free or the uncombined state bears oxidation number zeroD. In all its compounds, the oxidation number of fluroine is -1 |
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Answer» Correct Answer - a Oxidation number of hydrogen is always +1 is a wrong rule since, it is +1 in hydrogen halides, -1 in hydrides and zero in `H_(2)` molecule. All the other three statements (b), ( c) and (d) are correct |
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| 1089. |
Thiosulphate reacts differently with iodine and bromine in the reaction given below `2S_(2)O_(3)^(2-) to S_(4)O_(6)^(2-)+2I^(-)` `S_(2)O_(3)^(2-)+2Br_(2)+5H_(2)Oto2SO_(4)^(2-)+2Br^(-)+10H^(+)` Which of the following statements justifies the above dual behaviour of thiosulphate?A. Bromine is a stronger oxidant than iodineB. Bromine is a weaker oxidant than iodineC. Thiosulphate undergoes by bromine and reduction by iodine in these reactionsD. Bromine undergoes oxidation and iodine undergoes reduction in these reactions |
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Answer» Correct Answer - a `2overset(+2)(S_(2))overset(-2)(O_(2)^(2-))(aq)+I_(2)^(0)(s)tooverset(2.5)(S_(4))O_(6)^(2-)(aq)+2I^(-)(aq)` `overset(+2)(S_(2))overset(-2)(O_(3)^(2-))(aq)+2overset(0)(B)r_(2)(l)+5H_(2)O(l)to2overset(+6)(S)overset(2-)(O_(4)^(2-))(aq)+4Br^(-)(aq)+10H^(+)(aq)` Bromine being stronger oxidising agent than `I_(2)`, oxidises S of `S_(2)O_(3)^(2-)` to `SO_(4)^(2-)` whereas `I_(2)` oxidises it only into `S_(4)O_(6)^(2-)` ion. |
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| 1090. |
What mass of `Na_(2)S_(2)O_(3).5H_(2)O` is needed to make `500 cm^(3)` of `0.200N` solution for the reaction? `2S_(2)O_(3)^(2-)+I_(2)rarrS_(4)O_(6)^(2-)+2I^(-)` |
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Answer» Meq. of `Na_(2)S_(2)O_(3) = 0.2 xx 500 = 100` `(because Meq. N = xx V_((i n mL)))` `therefore` `(w)/(M//1) xx 1000 = 100` , `(because Meq. = (wt)/(E.wt) xx 1000)` or `(w)/(248) xx 1000 =100` `("Mol. wt" Na_(2)S_(2)O_(3). 5H_(2)O = 248)` `w = 24.8 g` |
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| 1091. |
`25ml` of `0.017H_(2)SO_(4)` in strongly acidic medium required `16.9mL` of `0.01M KMnO_(4)` and in neutral medium required `28.6mL` of `0.01MKMnO_(4)` for complete conversion fo `SO_(3)^(2-)` to `SO_(4)^(2-)` .Assign the oxidation no of `Mn` in the product formed in each case. |
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Answer» `SO_(3)^(2-)rarrSO_(4)^(2-)` `S^(4+)rarrS^(6+)+2e` `therefore ` Valence factor of `SO_(3)=2` In acid medium: Meq.of `SO_(3)^(2-)="Meq.of" MnO_(4)^(-)` `25xx0.017xx2=16.9xx0.01xxn_(1)` `therefore n_(1)=5` `therefore Mn^(7+)+5erarrMn^(4+)` In neutral medium: Meq.of `SO_(3)^(2-)=` Meq.of `MnO_(4)^(-)` `25xx0.017xx2=28.6xx0.01xxn_(2)` `therefore n_(2)=3` ltbr. `therefore Mn^(7+)+3e rarrMn^(4+)` |
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| 1092. |
Indicate the oxidation number of underlined, `Ba(H_(2)ul(P)O_(2))_(2)` |
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Answer» Let the oxidation number of `P` be `a`. `2+2xx[2xx1+a+2xx(-2)]=0` `a= +1` |
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| 1093. |
x mol of oxalate `FeC_(2)O_(4).Fe_(2)(C_(2)O_(4))_(3).2H_(2)O` on reaction with `Al_(2)(Cr_(2)O_(7))_(3)` requires 500mL 0.4M of it. Select the correct statement(s)A. n-factor of `Al_(2)(Cr_(2)O_(7))_(3)` is 6B. n-factor of `Al_(2)(Cr_(2)O_(7))_(3)` is 18C. Moles of oxalate which react with ` Al_(2)(Cr_(2)O_(7))_(3)` is 0.4D. Moles of oxalate which react with ` Al_(2)(Cr_(2)O_(7))_(3)` is 0.65 |
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Answer» Correct Answer - b,c |
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| 1094. |
Consider the reaction: `2S_(2)O_(3)^(2-)(aq)+I_(2)(s) rarr S_(4)O_(6)^(2-)(aq) + 2I^(Θ)(aq)` `2S_(2)O_(3)^(2-)(aq) + 2Br_(2)(l) + 5H_(2)O(l) rarr 2SO_(4)^(2-)(aq) + 4Br^(Θ)(aq)+10H^(o+)(aq)` Why does the same reductant, thiosulphate, react differently with iodine and bromine? |
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Answer» `I_(2)` Oxidises thiousuplhate ion to tetrathionate ion i.e, from O.S of +2 for `S (" in " S_(2)O_(3)^(2-) "to" S.O of + 5//2 "for" S ("in" S_(4)O_(6)^(2-) "ion")` `Br_(2)` oxidises thousuplhate ion to sulphate ion i.e from O.S of + 2 for `S("in "S_(2)O_(3)^(2-)) "to" O.S of + 6` for `S ("in "SO_(4)^(2-)ion)` This is because `Br_(2)` is a stronger O.A than `I_(2)(E^(@)_(Br_(2)//2Br-)=1.09V,E^(@)_(I_(2//2I^(-))=0.54V)` |
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| 1095. |
The oxidation state of nitrogen is correctly given forA. Compound = `[CO(NH_(3))_(5)Cl]Cl_(2)`, Oxidation state = `0`B. Compound = `NH_(2)OH` , Oxidation state = `-2`C. Compound =`(N_(2)H_(5))_(2)SO_(4)` , Oxidation state = `+2`D. Compound = `Mg_(3)N_(2)` , Oxidation state = `-3` |
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Answer» Correct Answer - D a. `[Co^(3+)(Noverset(0)H_(3))_(5)Cl^(1-)]^(+2)Cl_(2)^(-1xx2)` `NH_(3), x+3=0impliesx= -3` Oxidation state of `N = -3` b. `NH_(2)OH:x+3-2=0impliesx= -1` Oxidation state of `N= -1` c. `(N_(2)H_(5))_(2)^(+1xx2)SO_(4)^(2-)`: `N_(2)H_(5)^(o+): 2x+5= +1implies x= -2` d. `overset(+2xx3-3xx2)(Mg_(3)N_(2)): "Oxidation state of" N =-3` |
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| 1096. |
Oxidation number of carbon is correctly given forA. `{:("Compound","O.N."),("HN" overset(rarr)(=)C,+2):}`B. `{:("Compound","O.N."),(H-C-=N,+4):}`C. `{:("Compound","O.N."),(C Cl_(4),+4):}`D. `{:("Compound","O.N."),(C_(6)H_(12)O_(6),0):}` |
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Answer» Correct Answer - C::D In `C Cl_(4)` it is +4 and in `C_(6)H_(12)O_(6)` it is zero (Already discussed earlier) |
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| 1097. |
Various oxidation states of few elements are mentioned. Which of the options is not correctly matched ?A. Phosphorus: +3 to +5B. Nitrogen : +1 to +5C. Iodine : -1 to +7D. Chromium : -3 to +6 |
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Answer» Correct Answer - D Chromium does not show negative oxidation state. |
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| 1098. |
0,185g of an iron wire containing `99.8%` iron is dissolved in an acid to from ferrous ions. The solution requires 33mL of `K_(2)Cr_(2)O_(7)` solution for complete reaction. The normality of the `K_(2)Cr_(2)O_(7)` solution is :A. `0.05`B. `0.20`C. `0.02`D. `0.10` |
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Answer» Correct Answer - d |
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| 1099. |
Which of the following oxidation numbers is not correctly matched ?A. `HClO_(4)`B. N in `[Ni(CN)_(6)]^(4-)=+2`C. P in `Mg_(2)P_(2)O_(7)=+6`D. Cr in `(NH_(4))_(2)Cr_(2)O_(7)=+6` |
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Answer» Correct Answer - C `Mg_(2)P_(2)O_(7)=+5` `2(+2)+2x-14=0` `2x=10 rArr x= +5` |
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| 1100. |
The exhibition of various oxidation states by an element is also related to the outer orbital electornic configuration of its atom. Atom(s) having which of the following outermost electronic confjigurations will exhibit more than one oxidation state in its compoundsA. `3s^(-1)`B. `3d^(1)4s^(2)`C. `3d^(2)4s^(2)`D. `3s^(2)3p^(3)` |
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Answer» Correct Answer - b,c,d Elements which have only s-electrons in the valence shell do not show more than one oxidation state. Thus, element with `3s^(1)` as outer electronic configuration shows only one oxidation state of +1. Transition element such as elements (b), (c ) having incompletely filled d-orbitals in the penultimate shell show variable oxidation states. Thus, element with outer electronic configuration as `3d^(1)4s^(2)` shows variable oxidation states of +2 and +3 and the element with outer electronic configuration as `3d^(2)4s^(2)` shows variable oxidation states of +2, +3 and +4. p-Block elements also show variable oxidation states due to a number of reason such as involvement of d-orbitals and inert pair effect e.g., element (d) with `3s^(2)3p^(3)` as (i.e., P) as the outer electronic configuration shows variable oxidation states of +3 and +5 due to involvement of d-orbitals |
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