Explore topic-wise InterviewSolutions in Current Affairs.

This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.

1.

BeO and Be(OH)_(2) are amphoteric while the oxides and hydroxides of other alkaline earth metals are basic. The solubility of hydroxides increases as we move down the group from Be to Ba but the solubility of sulphates and carbonates decreases in that order the thermal stability of carbonates and sulphates of alkaline earth metals increases from Be to Ba as we move from top to bottom in the group. Which of the following metal carbonates decompses on heating ?

Answer»

`MgCO_(3)`
`Na_(2)CO_(3)`
`K_(2)CO_(3)`
`Rb_(2)CO_(3)`

Solution :`MgCO_(3)` DECOMPOSES on heating to give `MgO` and `CO_(2)`. While alkaline metal carbonates `(Na_(2),CO_(3),K_(2)CO_(3),Rb_(2)CO_(3)`} DONOT decompose.
Discussion
2.

Benzyl cation is stabilized by

Answer»

RESONANCE
hyperconjugation
both (a) & (B)
inductive

Solution :Resonance
Discussion
3.

Benzyl carbocation is more stable than ethyl carbocation. Justify.

Answer»

Solution :In ETHYL carbocation, there is only hyper-conjugation of the three `alpha`-hydrogen ATOMS and as a result, the following CONTRIBUTING structures are feasible.

But benzyl carbocation is more STABLE due to the presence of resonance and the following resonating structures are possible :
Discussion
4.

Benzylbromideis treated withhydrogen inpresenceof Pd -C.

Answer»

Solution :HYDROGENOLYSIS(cleavage of C-Br bond WITHHYDROGEN ) occursto formtoluene
`UNDERSET("Benzyl bromide")(C_(6)H_(5) -CH_(2) -Br +)H_(2) overset(Pd-C)(to) underset("TOLUENE")(C_(6)H_(5) -CH_(3)+HBr)`
Discussion
5.

Benzyl amine reacts with nitrous acid to form

Answer»

azobenzene
benzene
benzyl alcohol
phenol

Solution :`underset("Benzylamine")(C_(6)H_(5)CH_(2)NH_(2))+HONO_(2) RARR underset("Benzyl alcohol")(C_(6)H_(5)CH_(2)OH)+N_(2)+H_(2)O`
Discussion
6.

Benzyl alcohol is obtained from Benzaldehyde by

Answer»

FITTING's REACTION
CANNIZZARO's reaction
Kolbe's reaction
Wurtz's reaction

Solution :SEE Cannizzaro's reaction in ALDEHYDES.
Discussion
7.

Benzoyl chloride on treatment with ammonia gives

Answer»

Benzamide
Acetamide
Benzylamine
Benzoic acid

Solution :`C_(6)H_(5)COCl + 2NH_(3) rarr underset("Benzamide")(C_(6)H_(5)CONH_(2) + NH_(4)CL`
Discussion
8.

Benzoyl chloride is prepared from benzoic acid by :

Answer»

`Cl_(2), HV`
`SO_(2)Cl_(2)`
`PCl_(5)`
`Cl_(2)H_(2)O`

SOLUTION :SEE properties of acids
Discussion
9.

Benzoyl chloride is prepared from benzoic acid by

Answer»

`Cl_(2), hv`
`SO_(2)Cl_(2)`
`SOCl_(2)`
`Cl_(2), H_(2)O`

SOLUTION :
Discussion
10.

Benzophenone can be obtained by Friedel Crafts reaction beteween benzene and

Answer»

BENZYL chloride
Chlorobenzene
Benzoyl choride
None of these

Solution :
Discussion
11.

Benzontrichoride reacts with milk of lime to form :

Answer»

Benzal
Benzoic acid
Bennzyl ALCOHOL
Phenol

Solution :
Discussion
12.

Benzolation of phenol in alkaline medium is known as

Answer»

FRIEDEL CRAFT's reaction
Wurtz FITTING reaction
Schotten-Baumann reaction
Sabatier Sendren's reaction

Answer :C
Discussion
13.

Benzoic acid reacts with bromine to give

Answer»

`o-`bromobenzoic acid
`m-`bromobenzoic acid
`p-`bromobenzoic acid
3, 4-dibromobenzoic acid.

Solution :`-COOH` is a meta - DIRECTING GROUP
Discussion
14.

Benzoic acid mixed with napthalene can be purified by

Answer»

TREATING the mixture with HOT water
SUBLIMATION
Treating the mixture with cold water
DISSOLVING the mixture in benzene

Answer :D
Discussion
15.

Benzoic acid is an organic compound. Its crude sample can be purified by crystallisation from hot water. What characteristic differences in the properties of benzoic acid and the impurity make this process of purification suitable ?

Answer»

Solution :Benzoic acid can be purified from hot water because of the FOLLOWING characteristics.
(i) Benzoic acid is more soluble in hot water and less soluble in cold water.
(II) Impurities associated with benzoic acid are either insoluble in water or are more soluble in water to such an extent that when a hot saturated solution of benzoic acid is cooled, the impurities remain in the solution.
SINCE, IMPURE benoic acid satisfies both these conditions, therefore, benzoic acid can be purified by crystallization.
Discussion
16.

Benzoic acid is an organic compound. Its crude sample can be purified by crystallisation from hot water. What characteristic differences in the properties of benzoic acid and the impurity make this process of purification suitable?

Answer»

Solution :Benzoic ACID can be purified from hot water because of the FOLLOWS characteristics.
(i) Benzoic acid is more SOLUBLE in hot water and LESS soluble in cold water. (ii) Impurities associated with benzoic acid are either insoluble in water or are more soluble in water to such an extent that when a hot saturated solution of benzoic acid is cooled, the impurities remain in the solution.
Discussion
17.

Benzoic acid is a monobasic acid. When 1.22 g of its pure sample are dissolved in water and titrated against base, 50 ml of 0.2 M NaOH are used up. Calculate the molar mass of benzoic acid.

Answer»

Solution :1000 ml of 1 MNaOHwill NEUTRALIZE acid `=(1.22)/(50xx0.2)xx1000=122 G`
But 1000 ml of 1 M NaOH contain 1 mole of NaOH and will neutralize 1 mole of monobasic acid. Hence, MOLAR mass of BENZOIC acid `= 122 g"mol"^(-1)`.
Discussion
18.

Benzoic acid gives benzene on being heated with X and phenol gives benzene on being heated with Y. Therefore X and Y are respectively

Answer»

SODALIME and copper
ZINC DUST and SODIUM hydroxide
Zinc dust and sodalime
Sodalime and zinc dust

Solution :Sodalime and zinc dust
Discussion
19.

Benzoic acid can be purified by

Answer»

Sublimation
CRYSTALLIZATION
Distillation
Chromatography

SOLUTION :Because it is LESS SOLUBLE
Discussion
20.

Benzenesulphonic acid when heated with steam gives benzene but nitrobenzenedoes not. Why so ?

Answer»

SOLUTION :Sulphonation is a reversible reaction. When heated with excess of conc. `H_2SO_4`, the reaction moves in the forward direction giving benzenesulphonic acid and `H_2O`. However, when benzenesulphonic acid is heated with excess of steam , the reaction moves in the backward direction giving benzene and `H_2SO_4`.
`underset"Benzene"(C_6H_6)+H_2SO_4 overset"Heat"to underset"Benzenesulphonic acid"(C_6H_5SO_3H)+H_2O`
`underset"Benzenesulphonic acid"(C_6H_5SO_3H)+underset"Steam"(H_2O) overset"Heat"to underset"Benzene"(C_6H_6)+ H_2SO_4`
In CONTRAST, NITRATION is an irreversible reaction. THEREFORE, when nitrobenzene is heated with steam, backward reaction does not OCCUR and hence nitrobenzene is recovered .
`underset"Benzene"(C_6H_6)+underset"Conc."(HNO_3) overset(Conc. H_2SO_4)to underset"Nitrobenzene"(C_6H_5NO_2)+H_2O`
Discussion
21.

Benzene, when treated with CH_(2)O (methanal) in presence of HCl, undergoes chloromethylation to form benzyl chloride (C_(6)H_(5)CH_(2)Cl). If the produc is further treated with AlCl_(3) then expected product(s) is/are

Answer»




SOLUTION :
Discussion
22.

Benzene vapour mixed with air when passed over V_2O_5catalyst at 775 K give

Answer»

glyoxal
oxalic ACID
maleic ANHYDRIDE
fumaric acid.

Answer :C
Discussion
23.

Benzene undergoes both Friedel-Crafts alkylation and acylation reactions, with long n-alkyl chains, often rearranged products are obtained. Therefore, to prepare benzene derivatives with n-alkylchains either Friedel-Crafts acylation or some other suitable method is employed. , Compound X is

Answer»




SOLUTION :
Discussion
24.

Benzene undergoes both Friedel-Crafts alkylation and acylation reactions, with long n-alkyl chains, often rearranged products are obtained. Therefore, to prepare benzene derivatives with n-alkylchains either Friedel-Crafts acylation or some other suitable method is employed. Wurtz-Fittig reaction between bromobenzene and n-propyl bromide in presence of metalic solution in dry ether predominantly gives

Answer»

n-propylbenzene
ISOPROPYLBENZENE
n-hexane
BIPHENYL

SOLUTION :n-propylbenzene
Discussion
25.

Benzene undergoes both Friedel-Crafts alkylation and acylation reactions, with long n-alkyl chains, often rearranged products are obtained. Therefore, to prepare benzene derivatives with n-alkylchains either Friedel-Crafts acylation or some other suitable method is employed. Using anhydrous AiCl, as catalyst, which one of the following reactions produces ethylbenzene(PhEt)?

Answer»

`CH_3CH_2 OH + C_6H_6`
`CH_3CH = CH_2 + C_6H_6`
`H_2C = CHCl + C_6H_6`
`CH_3 - CH_3 + C_6H_6`

SOLUTION :FRIEDEL CRAFT alkylation
Discussion
26.

Benzene undergoes birch reduction to form ……..

Answer»




ANSWER :C
Discussion
27.

Benzene undergoes Birch reduction to form.............

Answer»





SOLUTION :
Discussion
28.

Benzene under goes electrophilic substitution reactions like nitration, sulphonation, halogenation, friedel crafts alkylation and friedel crafts acylation etc. . . Among these Friedel crafts alkylation and acylation are important, which are conducted in presence of lewis acid catalyst and suitable reagent. Q. Here 'Y' is

Answer»




SOLUTION :REARRANGEMENT of CARBOCATION is POSSIBLE.
Discussion
29.

Benzene under goes electrophilic substitution reactions like nitration, sulphonation, halogenation, friedel crafts alkylation and friedel crafts acylation etc. . . Among these Friedel crafts alkylation and acylation are important, which are conducted in presence of lewis acid catalyst and suitable reagent. Q. Here 'X' can be

Answer»




SOLUTION :INTERMEDIATE carbonion is NORE STABLE in the CASE
Discussion
30.

Benzene ring containsalternate single and double bonds, yet alll the C-C bonds are of equal length. Why ?

Answer»

SOLUTION :This is DUE RESONANCE in BENZENE .
Discussion
31.

Benzene ring contains ____ localised sigma - and ____localised pi -bonds.

Answer»


ANSWER :F
Discussion
32.

Benzene reacts with ______ to yield acetophenone

Answer»

`CH_(3)COCl+AlCl_(3)`
`C_(6)H_(3)COCl+AlCl_(3)`
`R-COCl+AlCl_(3)`
`C_(2)H_(5)COCl+AlCl_(3)`

Answer :A
Discussion
33.

Benzene reacts with -------- to yield acetophenone

Answer»

`CH3COCI + AICI_3`
`C_6H_5COCI + AICI_3`
`R COCI + AICI_3`
`C_2H_5COCl + AICI_3`

ANSWER :A
Discussion
34.

Benzene reacts with I_2 in presence of which of the following to give iodobenzene ?

Answer»

`HNO_3`
HI
`SO_2`
`H_2O`

Solution :Iodination OCCURS in PRESENCE of an OXIDISING agent `(HNO_3)`
Discussion
35.

Benzene reacts with Cl_2 in the presence of sunlight to give....

Answer»

BHC
PET
`SO_2`
`SO_3`

SOLUTION :BHC ( BENZENEHEXACHLORIDE )
Discussion
36.

Benzene reacts with H_(2) in the presence of Pt to give ..............

Answer»

SOLUTION :CYCLOHEXANE
Discussion
37.

Benzene reacts with Cl_(2) in the presence of FeCl_(3) and in absence of sunlight to form

Answer»

CHLOROBENZENE
Benzyl chloride
Benzal chloride
Benzene hexachloride

Solution :Chlorobenzene
Discussion
38.

Benzene reacts with Cl_2 in the presence of FeCl_3and in absence of sunlight to form

Answer»

CHLOROBENZENE
BENZYL CHLORIDE
Benzal chloride
Benzene hexachloride

Solution :Chlorobenzene
Discussion
39.

Benzene reacts with chlorine in presence of sun light gives a compounds (A). The compound and its use are

Answer»

`C_(6)Cl_(6)` INSECTICIDE
`C_(6)G_(6)Cl_(6)` insecticide
`C_(6)H_(5)Cl` insecticide
`C_(6)H_(6)Cl_(6)` sterlising agent

Answer :C::D
Discussion
40.

Benzene reacts with CH_(3)COCl in the presence of anhydrous AlCl_(3) to give

Answer»

`C_(6)H_(5)CH_(5)`
`C_(6)H_(5)CL`
`C_(6)H_(5)O_(2)Cl`
`C_(6)H_(5)COCH_(3)`

Solution :
Discussion
41.

Benzene reacts with chlorine in presence of sun light gives a compound(A). The compound and its use are

Answer»

`C_(6)Cl_(6)`, INSECTICIDE
`C_(6)H_(6)Cl_(6)`, insecticide
`C_(6)H_(5)CL`, insecticide
`C_(6)H_(6)Cl_(6)`, sterlising agent

Answer :B::C::D
Discussion
42.

"Benzene posses double bond though it is stable". Explain.

Answer»

Solution :Benzene possess double bond though it is stable.
(i) According to Kekule, benzene has two resnating structures.

(ii) Benzene has STABILITY of 36.0 k Cal according to resonance. So, in benzene there is no localization of doubly bonded electrons.

(iii) In benzene no there double bonds but according to molecular orbital theory, delocalization of electron above and below the plane of ATOM is POSSIBLE.

(iv) Benzene is aromatic. So from above all four REASONS, in reality benzene has no stabilize double bond in benzene and hence benzene is stable.
Discussion
43.

Benzene on reaction with ICI in presence of anhydrous AlCl_(3) gives?

Answer»




Solution :When `Icl` is HEATED with `AlCl_(3),I^(+)overset(ODOT)(A)lCl_(4)` complex formation is more farourable than `Cl^(+)overset(odot)(A)lCl_(3)l` complex. So iodiobenzene is FORMED.
Discussion
44.

Benzene molecule

Answer»

TRIGONAL
TETRAHEDRAL
PLANAR
PYRAMIDAL

SOLUTION :Planar
Discussion
45.

Benzene istreatedwithisobutylalcoholin presenceof conc. H_(2)SO_(4)

Answer»

Solution :In PRESENCE ofconc.`H_(2)SO_(4)` , ISOBUTYL alcoholfirstgenerates a `1^(@)` carbocationwhichthenundergoes rearrangementby 1,2-hydride shiftto forma morestabletert-butylcarbocation. Thissubsequentlyreacts withbenzene toformtert-butylbezene.
Discussion
46.

Benzene is statble. Why?

Answer»

Solution :BENZENE is stable because does not decolourise bromine is `"CCl"_(4)` solution and it does not decolurise COLD alkaline `"KMNO"_(4)` solution . This shows that benzene cannot be UNSATURATED as an alkene or alkyne.
Discussion
47.

Benzene is a resonance hybrid of mainly two Kekule structures. Hence

Answer»

Hlaf the molecules correspond to one structure and half to the second structure
At low temperature BENZENE can be separated into two STRUCTURES
Two structures MAKE equal CONTRIBUTION to resonance hybride
An INDIVIDUAL benzene molecule changes back and forth between two structures

Solution :Resonance
Discussion
48.

Benzene is aromatic because ……… (i) it has six carbon. (ii) all carbon has sp^(2) hybridization. (iii) it has three C=C. (iv) it has more proportion of carbon and less proportion of hydrogen. (v) it is planner in nature.

Answer»


ANSWER :(i-F), (ii-F), (iii-F), (iv-T), (v-F)
Discussion
49.

Benzene gives ……….. type of reaction easily.

Answer»

SOLUTION :ELECTROPHILIC AROMATIC SUBSTITUTION.
Discussion
50.

Benzene has planar structure.

Answer»


ANSWER :T
Discussion