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.

Phenol is an antiseptic because of its _____________

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toxic EFFECT on micro-organisms
associated MOLECULES
high melting and BOILING POINTS
acidic CHARACTER

Answer :A
2.

Phenol is acidic because of resonance stabilization of its conjugate base, namely______.

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SOLUTION :PHENOXIDE ION
3.

Phenol is an acid but does not react with sodium bicarbonate solution. Explain.

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SOLUTION :Phenol is a weaker acid than CARBONIC acid `(H_(2)CO_(3))` ANND hence does not liberate `CO_(2)` from SODIUM bicarbonate.
4.

Phenol is also known as

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PHENOLIC acid
Hydroxy cinnamic acid
CARBOLIC acid
Hydroxy carbolic acid

Answer :C
5.

Phenol is a very weak acid. What substitutions in the molecule can make it a stronger acid and a weaker acid and why?

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Solution :Phenol is very weak acid. Electron withdrawing groups like `-NO_(2)` will INCREASE ACIDIC character due to stabilisation of PHENOXIDE ION whereas electron releasing groups like `-CH_(3)` will make it weaker acid because of destabilisationo f phenoxide ion.
6.

Phenol is a very _____ .

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WEAK ACID
weak base
Both
none

Answer :weak acid
7.

Phenol is a bifunctionalcompound because ______.

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it GIVES reactions of HYDROXYL group (-OH) as well as of aromatic ring
it is a strong ACID
it is insoluble in NaOH
it is readily soluble in water

ANSWER :A
8.

Phenol is....

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STRONG BASE than ammonia
WEAK ACID than CARBONIC acid
strong acid than carbonic acid
neutral compound

Solution :weak acid than carbonic acid
9.

Phenol is

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a weakerbase than `NH_3` .
strongeracid than CARBONIC ACID
weakeracid than carbonic acid
a neutralcompound

ANSWER :C
10.

Phenol has __________ nature and is __________ in H_2O .

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hydroscopic, easily soluble
hydroscopic, SPARINGLY soluble
hydrophilic , HIGHLY soluble
HYGROSCOPIC, highly soluble

ANSWER :B
11.

Phenol is …….

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ACIDIC
Basic
Neutral
Amphoteric

Solution :Acidic
12.

Phenol gives which product of reaction with acid anhydried or acid chloride in alkali medium ?

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PHENYL ester
Phenyl ether
Phenyl acid
Phenyl amine

Answer :A
13.

phenol gives violet colouration with _____solution.

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ANSWER :FERRIC CHLORIDE SOLUTION.
14.

Phenol gives violet colour with

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NEUTRAL `FeCl_3`
neutral `FeSO_4`
ACIDIC `FeCl_3`
acidic `FeSO_4`

ANSWER :A
15.

Phenol gives tribromophenol when treated withbromine inaqueous solutionby only o- and p- bromophenolsinCCl_(4) solutionbecause

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in aqueous SOLUTION the brominein ionised
in aqueoussolution,phenolexists in EQUILIBRIUM withphenoxideion WHICHHAS more activating effect
in `CCI_(4)` the electrophilicity of `Br_(2)` increase
in `CCI_(4)` the other positions of benzene rings are blocked by the solvent.

Solution :N/A
16.

Phenol forms coloured complexes with neutral_______.

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SOLUTION :FERRIC CHLORIDE
17.

Phenol gives characteristic colouration with

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IODINE solution
BROMINE water
Aqueous `FeCl_3 ` solution
AMMONIUM HYDROXIDE

Answer :C
18.

Phenol gives salicylaldehyde onheating withCHCl_3 and NaOH. The reaction is called:

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CANNIZZARO's reaction
wurtzreaction
Reimer-Tiemann reaction
Perkin 's reaction

Answer :C
19.

Phenol formaldehyde is known as ………………….. .

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SOLUTION :BAKELITE
20.

Phenol easily dissolves in _________.

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ETHER
ETHANOL
WATER
Both A and B

ANSWER :D
21.

Phenol do not react with

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POTASSIUM hydroxide
Sodium carbonate
Sodium hydroxide
Sodium bicarbonate

Answer :D
22.

Phenol does not react with sodium carbonate. Why?

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SOLUTION :DUE to RESONANCE stablisation.
23.

Phenol decolourises reddish brown colour of bromine, though it is not unsaturated compound. Explain.

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Solution :Phenol is highly REACTIVE with `Br_2-H_2O` and FORMS 2, 4, 6-tribromophenol. The REACTION is electrophelile substitution with liberation of HBR.
HENCE, the colour of bromine disappears.
24.

Phenol (CHCl_(3)//NaOH) underset(H^(+)) to Salicyldehyde. The above reaction is known as

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Rimer-Tiemann REACTION.
Bucherer reaction.
GATTERMANN synthesis.
Perkin reaction

Answer :A
25.

Phenol can be separated from Benzoic acid effectively by the use of

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`NaHCO_(3)`
NAOH
`aq NH_(3)`
NONE of these

Solution :Benzoic acid reacts while PHENOL does not .
26.

Phenol can be prepared from

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BENZENE DIAZONIUM chloride
Chlorobenzene
SODIUM benzene sulfonate
All

Answer :D
27.

Phenol can be prepared from ________.

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SODIUM PHENOXIDE
CHLOROBENZENE
sodium BENZENE sulphonate
all of these

ANSWER :D
28.

Phenol can be prepared by the reaction between

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Aniline and `HNO_3`at 373 K
`C_6H_5MgBr`and `CO_2`followed by HYDROLYSIS
`C_6H_5Cl`and NAOH at 373 K
`C_6H_5SO_3Na`and NaOH at 573-623K followed by acidification

Answer :D
29.

Phenol can be distinguished from ethyl alcohol by all reagents EXCEPT ________.

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`I_2+NaOH`
NEUTRAL `FeCl_3`
`Br_2//H_2O`
`NA`

ANSWER :D
30.

Phenol can be distinguished from ethanol the reaction with ….

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`Br2//"water"`
Na
NEUTRAL `FeCl_(3)`
All of the above

Solution :Phenol with neutral `FeCl_(3)` gives a VIOLET complex whereas ethanol forms YELLOW hexagonal crystals of IODOFORM when heated with alkaline solution of IODINE. Phenol also forms a tribromo derivate which is not given by alcohol.
31.

Phenol can be distinguished from ethanol by the reagent

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BROMINE water
sodium METAL
iron metal
CHLORINE water

Solution :Phenol gives white precipitate with excess of bromine water DUE to the formation of 2, 4, 6-tribromophenol.

ALCOHOL does not react with bromine water.
32.

Phenol can be distinguished from ethanol by the reaction with ____________.

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`Br_(2)//"WATER"`
`Na`
`"Nautral "FeCl_(3)`
All the above

Answer :A::C
33.

phenolcan be distinguishedfromethanolby thereactionwith_______.

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`Br_2 //`WATER
`NAOL`
Nautral`FeCl_3`
All the above

Answer :D
34.

Phenol can be distinguished from ethanol by thefollowing reagents except

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SODIUM<BR>`NaOH//I_(2)`
Neutral `FeCl_(3)`
`Br_(2)//H_(2)O`

SOLUTION :
35.

Phenol at25^(@)C is _____________.

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a colourless crystalline SOLID
a TRANSPARENT LIQUID
a gas
yellow solution

ANSWER :A
36.

Phenol can be distinguished from ethanol by the reaction with ______.

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`Br_(2)`/water<BR>Na
neutral `FeCl_(3)`
All the above

Solution :Since Na REACTS with both ethanol and phenol, therrefore, it cannot be used to distinguish between them. Therefore, both the remaining two options, i.e., (a) and (c) are correct.
37.

Phenol can be distinguished from ethanol by the following reagents except …………………. .

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SODIUM
`NaOH//I_2`
Nautral `FeCl_3`
`Br_2//H_2O`

SOLUTION :Sodium
38.

Phenol can be distinguished from ethanol by

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TOLLEN's REAGENT
Benedict's reagent
`FeCl_(3)`
SCHIFF's base

Answer :C
39.

Phenol, C_(6)H_(5)OH when it first reacts with concentrated sulphuric acid, forms Y. The compound, Y is reacted with concentrated nitric acid to form Z. Identify Y and Z and explain why phenol is not converted commercially to Z by reacting it with conc. HNO_(3).

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SOLUTION :
Phenol is not reacted directly with conc. `HNO_(3)` because the yield of PICRIC ACID is very poor.
40.

Phenols can bedistinguishedfromalcoholsby

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NEUTRAL `FeCl_3`
`FeSO_4` SOLUTION
`BaCl_2` solution
IODOFORM REACTION

ANSWER :A
41.

Phenol (C_(6)H_(5)OH) gets associated in water to from double molecules. 0.6677 g of phenol dissolved in 35.5 g of water depresses the freezing point of water by 0.215. (K_(f) "for water"=1.86 K kg^(-1)mol^(-1)). Calculate Observed molar mass of phenol Degree of association of phenol.

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Solution :`Step I."Calculation of observedmolar mass of PHENOL."`
`M_(B)=(K_(f)xxW_(B))/(DeltaT_(f)xxW_(A))`
`K_(f)=1.86" K kg mol"^(-1),W_(B)=0.6667 g, DeltaT_(f)=0.215 K, W_(A)=35.5=0.0355 kg.`
`M_(B)=((186" K kg mol"^(-1))xx(0.6667g))/((0.215K)xx(0.0355 "kg"))=162.47" g mol"^(-1)`
Step II. Calculation of Van't HOFF factor (i).
`i=("Normall molar mass of phenol"(C_(6)H_(5)OH))/("OBSERVED molar mass of phenol")=((94"g mol"^(-1)))/((162.47" g mol"^(-1)))=0.579`
Step III. Calculation of degree of association of phenol.
`alpha=(i-1)/(1/n-1)=((0.579-1))/((0.5-1))=((-0.421))/((-0.5))=0.842.`
42.

Phenol associates in benzene to produce double molecules. To what degree phenol associates if van't Hoff factor is 0.54?

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0.54
0.92
0.98
0.46

Answer :B
43.

Phenol associates in benzene to a certain extent to form dimer. A solution containing 2.0xx10^(-2)kg of phenol in 1.0 kg of benzene has its freezing point decreased by 0.69 K. Calculate the degree of association of phenol (K_(f)" for benzene = 5.12 K kg mol"^(-1)).

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Solution :`M_(2)"(observed)"=(1000K_(f)w_(2))/(w_(1)DeltaT_(f))=("1000 g kg"^(-1)xx"5.12 K kg mol"^(-1)xx2.0xx10^(-2)kg)/(1.0kg xx0.69K)="148.4 g mol"^(-1)`
`M_(2)"(calculated) for "C_(6)H_(5)OH="94 g mol"^(-1)""therefore""i=(M_(2)"(calculated)")/(M_(2)"(observed)")=(94)/(148.4)=0.633`
`{:(,2C_(6)H_(5)OHhArr(C_(6)H_(5)OH)_(2)),("Initial","1mol"),("After asso."," "1-alpha""alpha//2"Total "=1-alpha//2):}`
`i=(1-alpha//2)/(1)"or"alpha=2(1-i)=2(1-0.633)=0.734.`
44.

Phenol associates in benzene to a certain extent to form a dimmer. A solution containing20 g of phenol in 1.0 kg of benzene has its freezing point lowered by 0.69 K. Calculate thefraction of phenol that has dimerised. [Given K_f for benzene = 5.1 K m^(-1)

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SOLUTION :`M_2` (OBSERVED) ` = (1000 K_f w_2)/(w_1 Delta T_f)`
SUBSTITUTING the values , we have
`M_2 = (1000 XX 5.12 xx 2 xx 10^(-2) )/(1.0 xx 0.69) = 148.g "mol"^(-1)`
`M_2` (calculated ) = 94 g/mol`i=(M_2("calculated"))/(M_2("observed") = (94)/(148.4) = 0.633`
The association can be EXPRESSED as under

where `alpha ` is the degree of association
`i= (1 - alpha//2)/(1) " or" alpha = 2(1 - i) = 2(1-0.633)= 0.734`
45.

Phenol associaes in bensen to a certain extent to from a dimer. A solution containing 2.0xx10^(-2) kg of phenol in 1.0 kg of benzene has a greezing point decreased by 0.69 K. What is the degree of association of phenol ? (K_(f) for benzene=5.12 K kg mol^(-1)).

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Solution :Step I. Calculation of OBSERVED molar mass of phenol
`M_(B)=(K_(f)xxW_(B))/(W_(A)xxDeltaT_(f))=((5.12" K kg mol"^(-1))xx(2.0xx10^(-2)kg))/((1.0kg)xx0.69K)`
`=14.84xx10^(-2)" kg mol"^(-1)=148.4" G mol"^(-1)`
Step II. Calculation of Van't Hoff factor
`"Van't Hoff factor (i)"=("Normal molar mass of phenol")/("Obsrved molar mass of phenol")`
`=((94" g mol"^(-1)))/((148.4" g mol"^(-1)))=0.633`
Step III. `"Calculation of DEGREE of association of phenol "(alpha)`
`2C_(6)H_(5)OHhArr(C_(6)H_(5)OH)_(2)`
`alpha=(i-1)/(1/n-1)=((0.633-1))/((1/2-1))=((-0.367))/((-0.500))=0.734 or 73.4`%
46.

Phenol associates in benzene to a certain extent to form a dimer. A solution containing 20 g of phenol in 1.0 kg of benzene has its freezing point lowered by 0.69 K. Calculate the fraction of phenol that has dimerised. [Given : K_(f) for benzene = 5.1 Km^(-1)]

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Solution :Association of phenol `C_(6)H_(5)OH (M_(B) = 94)`
`W_(B)=20` g ( Phenol )
`DeltaT_(F) `=0.69 K
`W_(A) =1` kg (Benzene fraction)
`K_(f) =5.1 km^(-1)`
Phenol dimerised
`DeltaT_(f)= iK_(f)m`
`0.69=ixx5.1xx(20)/(94xx1)`
`i =(94xx0.69)/(20xx5.1)`
`=(64.86)/(102.51)`
=0.63
`alpha=(i-1)/((1)/(n)-1)` (Association)
`=(0.63-1)/((1)/(2)-1)=(0.37)/(-0.5)`
`alpha=0.74`
or `= 74%`
47.

Phenol and formaldehyde undergo condensation to give a polymer (A) which on heating with formaldehyde gives a thermo- setting polymer (B). Name the polymers. Write the reactions involved in the formation of (A). What is the structural difference between two polymers ?

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Solution :Phenol and formaldehyde undergo CONDENSATION to give a polymer NOVOLAC (A) Which arc heating with formaldehyde GIVES BAKELITE (B) as a thermosetting polymer.
Sequences of the reaction can be WRITTEN as

Structural differences in between Novolac and bakelite is that nonolac is a lnear polymer while bakelite is a cross linked polymer.
48.

Phenol and succinic acid

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PHENOL and PHTHALIC ANHYDRIDE
Phenol and succinic anhydride
Phenol and BENZALDEHYDE
Phenol and benzaldehyde

Answer :B
49.

Phenol and ethanol are distinguished chemically by ……

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NEUTRAL `FeCl_(3)`
Fehling's reagent
Ammonical `Cu_(2)Cl_(2)`
TOLLEN's reagent

Solution :Neutral `FeCl_(3)`
50.

Phenol and formaldehyde undergo condensation to give a polyer (A) which on heating with formaldehyde gives a thermosetting polymer (B). Name the poylemers. Write the reactions involved in the formation of (A). What is the structural difference between two polymers ?

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SOLUTION :A' is novolac and 'B' is bakelite. For REACTIONS involved ANS structural DIFFERENCES.