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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.
| 1. |
Reimer-Tiemann reaction introduces an aldehyde group on to the aromatic ring of phenol, ortho to the hydroxyl group. This reacrtion involves electrophilic aromatic subsititution. It is a general method for the synthesis of subsituted salicyladehydes as depiced below: Which one of the following reagents is used in the above reaction ?A. aq. `NaOH+CH_(3)Cl`B. aq. `NaOH+CH_(2)Cl_(2)`C. aq. `NaOH+CHCl_(3)`D. aq. `NaOH+C Cl_(4)` |
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Answer» Correct Answer - C aq. `NaOH+CHCl_(3)`. |
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| 2. |
Reimer Tiemann reaction introduces an aldehyde group, on to the ring of phenol, ortho to hydroxyl group. The reaction involves electro-philic aromatic substitution. This is a general method for synthesis of substituted salicyladehyde as depicted below Which one of the following reagents is used in the above reactionsA. aq `NaOH+CH_(3)Cl`B. aq `NaOH+CH_(2)Cl_(2)`C. aq `NaOH+CH_(3)Cl_(3)`D. aq `NaOH+C Cl_(4)` |
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Answer» Correct Answer - C `NaOH aq+ CHCl_(3)` `Cl_(3)C-H underset(-H_(2)O)overset(OH^(-))rarr Cl_(3)C^(-)` |
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| 3. |
Both alcohols and phenols contain a hydroxyl group, but phenols are more acidic than alcohols. The reason being that the phenoxide ion left after the removal of a proton is resonance stabilized while alkoxide is not. Therefore, phenols dissolve in aqueous sodium hydroxide but alcohols do not. However, both are weaker acids than carbonic acid and hence do not decompose aqueous `NaHCO_(3)` solution evolving `CO_(2)`. The presence of electron-donating groups in the benzene ring decrease the acid strength while the presence of electron withdrawing groups in the benzene ring increase the acid strength of phenols. The relative strength of o-, m- and p- substituted phenols, however, depends upon a combination of inductive and resonance effects of the substituent. Alcohols are very weak acids even weaker than water. Because of the `+I` effect of the alkyl groups, tha acidic strength of alcohols decreases in the order : `1^(@)` alcohol `gt 2^(@)` alcohol `gt 3^(@)` alcohol. Which of the following is the strongest acidA. `FCH_(2)CH_(2)CH_(2)OH`B. `FCH_(2)CH_(2)CH_(2)OH`C. `CH_(3)CH_(2)CHFCH_(2)OH`D. `CH_(3)CH_(2)CF_(2)CH_(2)OH` |
| Answer» Correct Answer - D | |
| 4. |
Which one of the following compounds has the most acidic nature?A. B. C. D. |
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Answer» Correct Answer - A Phenyl is an electron withdrawing substituent and hence increases acidity. `-CH_(3)` is an electron releasing group and hence decrease acidity. Thus phenol is the most acidic among the given compounds. |
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| 5. |
How will you explain that phenols are acidic in nature ? |
| Answer» The reaction of phenol with metals(example: sodium, aluminium) and sodium hydroxide indicate its acidic nature.The hydroxyl group ,in phenol is directly attached to the SP2 hybridised carbon of benzene ring which acts as an electron withdrawing group.Due to this, the charge distribution in phenol molecule ,as depicted in its resonance structures, causes the oxygen of -OH group to be positive ,that's why phenols are acidic in nature. | |
| 6. |
Which of the following orders is true regarding the acidic nature of phenols ?A. Phenol `gt` o-cresol `lt` o-nitrophenolB. o-cresol `lt` phenol `lt` o-nitrophenolC. Phenol `lt` o-nitrophenol `lt` o-cresolD. o-nitrophenol `lt` o-cresol `lt` phenol |
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Answer» Correct Answer - B It is the true order. |
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| 7. |
Which one of the following compounds has the most acidic nature?A. B. C. D. |
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Answer» Correct Answer - B Phenol is the most acidic since electron withdrawing phenyl group is attached directly to `OH` group. As a result, release of `H^(+)` ion becomes easy. |
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| 8. |
Which one of the following is most reactive towards electrophilic reagent ?A. B. C. D. |
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Answer» Correct Answer - A In cresol, `CH_(3)` group has `+ I` effect and `-OH` group has `+M` effect. As a result, the ring gets maximum activated and the electrophile attack becomes easiest. |
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| 9. |
Assertion : Phenol is acidic in nature. Reason : Hydrid for phenate ion is less resonance stabilised than hybrid for phenol.A. If both assertion and reason are correct and reason is correct explanation for assertion.B. If both assertion and reason are correct but reason is not correct explanation for assertion.C. If assertion is correct but reason is incorrect.D. If assertion and reason both are incorrect. |
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Answer» Correct Answer - C Correct reason : Hybrid for phenate ion is more resonance stabilised than hydrid for phenol. |
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| 10. |
The best reagent to covert pent-3-en-2-ol into pent-3-en-2-one is :A. acidic permanganateB. acidic dichromateC. chromic anhydride in glacial acetic acidD. pyridine chlorochromate. |
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Answer» Correct Answer - D Pyridine chlorochromate `(PC C)` converts secondary alcohol to ketone without affecting double bond. |
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| 11. |
The best reagent to convert pent-3-en-2-ol into pent-3-in-2-on isA. Acidic permanganateB. Acidic dichromateC. Chromic anhydride in glacial acetic acidD. Pyridinium chloro-chromate |
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Answer» Correct Answer - D Pyridinium chlorochromate `(PC C, CrO_(3), C_(2)H_(5)N.HCl)` has an advantage over other oxidising agents that the oxidation of `1^(@)` alcohol stops at aldehyde stage (oxidation of aldehyde to carboxylic acid is prevented) and `2^(@)` alcohol containing doube bond is oxidised to ketone retaining the double bond (double bond is not affected). |
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| 12. |
Which of the following reagents is useful in separating benzoic acid from phenol ?A. Dil. HClB. Dil. `H_(2)SO_(4)`C. `5%` aqueous NaOHD. 5% aqueous `NaHCO_(3)` |
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Answer» Correct Answer - D Benzoic acid dissolves in an aqueous solution of `NaHCO_(3)`, while phenol being less acidic than `H_(2)CO_(3)` do not reacts. |
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| 13. |
The correct order of increasing basicity of the following is `H_(2)O, OH^(-), CH_(3)OH, CH_(3)O^(-)`A. `CH_(3)OH lt H_(2)O lt OH^(-) lt CH_(3)O^(-)`B. `H_(2)O lt CH_(3)OH lt CH_(3)O^(-) lt OH^(-)`C. `H_(2)O lt CH_(3)OH lt OH^(-) lt CH_(3)O^(-)`D. `CH_(3)OH lt H_(2)O lt CH_(3)O^(-) lt OH^(-)` |
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Answer» Correct Answer - C Alcohols are weaker acids than water. In other words alcohols are stronger bases than water. Both alcohol and water are weak acids as such their conjugate base of water `(OH^(-))` is weaker than alkoxide ion. `underset((("Weaker acid"),("stronger base")))(CH_(3)OH)` , `underset((("stronger acid"),("weaker base")))(H_(2)O)` `underset("weaker acid")(CH_(3)OH) hArr underset("stronger base")(CH_(3)O^(-))+H^(+)` `H_(2)O hArr OH^(-)+H^(+)` |
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| 14. |
The relative order of basicity of conjugate bases isA. `OH^(-) lt OR^(-) lt HC -= C^(-)`B. `OH^(-) lt HC -= C^(-) lt OR^(-)`C. `HC -= C^(-) lt OH^(-) lt OR^(-)`D. `HC -= C^(-) lt OR^(-) lt OH^(-)` |
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Answer» Correct Answer - A Strong acid will have a weak conjugate base and vice versa (Bronsted-Lowery concept of acids-base). Acidic charatcer of conjugate acids is `H_(2)O gt ROH gt HC -= CH` `:.` the order of basicity is `underset("weakest base")(OH^(-)) lt underset("strongest base")( RO^(-)lt HC -= C^(-))` |
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| 15. |
In reaction of alcohols with alkali metla, which of the following alcohol will react fastest?A. SecondaryB. TertiaryC. PrimaryD. All equal |
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Answer» Correct Answer - C Primary alcohol because the reaction involves cleavage of strongest acidic group `(O-H)` of various of alcohols. |
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| 16. |
Propan-1-ol can be prepared from propene byA. `H_(2)O //H_(2)SO_(4)`B. `Hg(OAc)_(2)//H_(2)O` followed by `NaBH_(4)`C. `B_(2)H_(6)` followed by `H_(2)O`D. `CH_(3)CO_(2)H//H_(2)SO_(4)` |
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Answer» Correct Answer - C `6CH_(3)CH=CH_(2)+B_(2)H_(6) rarr 2(CH_(3)CH_(2)CH_(2))_(3)B underset(OH^(-))overset(H_(2)O_(2))rarr 6CH_(3)CH_(2)CH_(2)OH+B(OH)_(3)`. |
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| 17. |
How will you convert ethanol to propan-2-ol ? |
| Answer» `underset("Ethanol")(CH_(3)CH_(2)OH)underset("(Oxidation)")overset(K_(2)Cr_(2)O_(7)//H_(2)SO_(4))(rarr)underset("Ethanal")(CH_(2)-overset(O)overset(||)(C)-H)overset(CH_(3)MgBr)(rarr)[CH_(3)-underset(CH_(3))underset(|)overset(" "OMgBr)overset(|)(C)-H]underset(H^(+))overset(H_(2)O)(rarr)underset("Propan-2-ol")(CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)(C)-H)` | |
| 18. |
How will you convert propene to propan -1-ol ? |
| Answer» `underset("Propene")(CH_(3)-CH=CH_(2)) underset((R-O-O-R))overset(HBr)(rarr)underset("1-Bromopropane")(CH_(3)-CH_(2)-CH_(2)Br) overset(KOH (aq))(rarr)underset("Propan-1-ol")(CH_(3)-CH_(2)-CH_(2)OH)` | |
| 19. |
1-Hydroxypropane can be obtained from propene by treating withA. `B_(2)H_(6)+NaOH`B. `B_(2)H_(6)+H_(2)O //OH^(-)`C. `LiAlH_(4) +H_(2)O //H^(+)`D. `HCl+H_(2)O //H^(+)`. |
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Answer» Correct Answer - B `CH_(3)CH=CH_(2) underset((ii)H_(2)O_(2)//OH^(-))overset((i)B_(2)H_(6))rarrCH_(3)CH_(2)CH_(2)OH` |
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| 20. |
Minimum percentage of ethyl alcohol by weight in its aqueous solution, so that gun powder soaked in the aqueous solution catches fire isA. `95.5%`B. `57.1%`C. `33.3%`D. `49.4%` |
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Answer» Correct Answer - D Gun powder soaked in under proof alcohol donot catch fire. |
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| 21. |
Zinc powder `+PH-OH rarr X`. In the above reaction the product X will beA. BenzaldehydeB. BenzeneC. AnisoleD. Phenyl acetate |
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Answer» Correct Answer - B `Ph-OH+Zn overset("Heat")underset("Benzene")(Ph-H+ZnO)` |
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| 22. |
The correct acidity order of the following is A. `(III) gt (IV) gt (II) gt (I)`B. `(IV) gt (III) gt (I) gt (II)`C. `(III) gt (II) gt (I) gt (IV)`D. `(II) gt (III) gt (IV) gt (I)` |
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Answer» Correct Answer - A A carboxylic acid is stronger acid then phenol, hence both III and IV are stronger acids than both I and II. Also IV has a methyl group that gives electron donating inductive effect and decreases the acid strength. Therefore, III is stronger acid than IV. Between I and II, the dominant electron withdrawing inductive effect of chlorine increases acid strength of phenol slightly, hence II is stronger acid than I. Thus, the overall order is : (A) `III gt IV gt II gt I`. |
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| 23. |
`R-OH+HX rarr RX+H_(2)O` In the above reaction, the reactivity of alcohols isA. Tertiary `gt` secondary `gt` primaryB. Tertiary `lt` secondary `lt` primaryC. Teritary `gt` primary `gt` secondaryD. Secondary `gt` primary `gt` tertiary |
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Answer» Correct Answer - A The presence of three electron releasing groups at `alpha`-carbon repel the bond pair of `C-OH` bond and facilitate its replacement. |
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| 24. |
In the following compounds, The order of acidity is :A. `III gt IV gt I gt II`B. `I gt IV gt III gt II`C. `II gt I gt III gt IV`D. `IV gt III gt I gt II` |
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Answer» Correct Answer - D Electron withdrawing groups (e.g., `NO_(2)`) increases the acidity of phenol. The effect of electron with-drawing group is more, if it is present at o- or p-position. On the othter hand, electron donating groups (e.g., `CH_(3)-`) make it less acidic. |
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| 25. |
Strength of acidity is in order A. `II gt I gt III gt IV`B. `III gt IV gt I gt II`C. `I gt IV gt III gt II`D. `IV gt III gt I gt II` |
| Answer» Correct Answer - B | |
| 26. |
The order of reactivity of alcohols with sodium metal isA. `3^(@) gt 2^(@) gt 1^(@)`B. `1^(@) gt 2^(@) gt 3^(@)`C. `2^(@) gt 3^(@) gt 1^(@)`D. `3^(@) lt 2^(@) gt 1^(@)` |
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Answer» Correct Answer - B `2ROH+2Na rarr 2RONa+H_(2)` In this reaction, alcohol acts as an acud. The acidic character of `1^(@), 2^(@)` and `3^(@)` alcohols is in the order `1^(@) gt 2^(@) gt 3^(@)`. |
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| 27. |
The vicimal diols can be detected by the reaction of the compound withA. `NaOH` and `I_(2)`B. conc. `H_(2)SO_(4)`C. `HIO_(4)`D. Acidified `KMnO_(4)` |
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Answer» Correct Answer - C `{:(CH_(2)-OH),("| " overset(HIO_(4))rarr2HCHO+H_(2)O+3[O]),(CH_(2)-OH):}` The vicinal diols can be detected with `HIO_(4)` or `Pb(CH_(3)COO)_(4)` |
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| 28. |
Given The decreasing order of their acidic character isA. `I gt II gt III`B. `II gt I gt III`C. `II gt III gt I`D. `III gt II gt I` |
| Answer» Correct Answer - C | |
| 29. |
Arrange the following compounds in order of decreasing acidity: A. `III gt I gt II gt IV`B. `IV gt III gt I gt II`C. `II gt IV gt I gt III`D. `I gt II gt III gt IV` |
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Answer» Correct Answer - A Electron withdrawing groups will increase the acidic character while electron releasing group will decrease the acidic character. Further R- effect is stronger than I-effect. Here, `-Cl` has `-I` effect and `+R` effect, `-CH_(3)` has weak `+I` effect, `-NO_(2)` has `-I` and `-R` effect and `-OCH_(3)` has `-I` and `+R` effect. Thus correct order is : `III gt I gt I gt IV`. |
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| 30. |
Which of the following is the most suitable method for removing the traces of water from ethanol?A. Reacting with Na metalB. Passing dry HCl through itC. Distilling itD. Reacting with Mg |
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Answer» Correct Answer - D `Mg+C_(2)H_(5)OH rarr Mg(OC_(2)H_(5))_(2)+H_(2)` `Mg(OC_(2)H_(5))_(2)+H_(2)O rarr MgO+2C_(2)H_(5)OH`. |
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| 31. |
Arrange the following gem diols in decreasing order of stability : A. `II gt II gt III`B. `III gt II gt I`C. `I gt III gt II`D. `III gt I gt II` |
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Answer» Correct Answer - A As the internal angle increases, the steric hindrance to the attacking apecies increases. This leads to decrease in stability of the cyclic diol. Therefore (a) is the correct order. |
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| 32. |
Identify the chiral molecule in the following pairs : |
| Answer» `{:(CH_(3)-CH-overset(**)(C)H-CH_(3),CH_(3)-CH-CH-CH_(2)-CH_(3)),(" |"" |"," |"" |"" |"),(" "CH_(3)" "OH," "CH_(3)" "OH" "CH_(3)),(" (i)"," (ii)"),(" 3-Methylbutan-2-ol"," 2, 4-dimethylpentan-3-ol"),("(Optically active or Chiral)"," (Optically inactive)"):}` | |
| 33. |
Which is the most suitable method for removing the traces of water from ethanol ?A. Heating with `Na` metalB. Passing dry `HCl` gas through it.C. Distilling itD. Reacting with `Mg`. |
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Answer» Correct Answer - D `C_(2)H_(5)OH` first reacts with `Mg` metal to form `(C_(2)H_(5)O)_(2)Mg`. `2C_(2)H_(5)OH+Mg rarr (C_(2)H_(5)O)_(2)Mg+H_(2)` `C_(2)H_(5)OH` can be regenerated by reacting `(C_(2)H_(5)O)_(2)Mg` with water `(C_(2)H_(5)O)_(2)Mg+2H_(2)O rarr Mg(OH)_(2)+2C_(2)H_(5)OH`. |
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| 34. |
Terylene is formed by the reaction of one of the following alcoholsA. 2-ChloroethanolB. EthanediolC. 1,2,3-PropanetriolD. Phenol |
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Answer» Correct Answer - B Ethanediol |
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| 35. |
Ethane-1,2-diol when heated with `ZnCl_(2)` givesA. EthanalB. EtheneC. Ethanoic acidD. Ethane |
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Answer» Correct Answer - A `{:(" "OH),(" |"),(HO-CH-H underset(-H_(2)O)overset(ZnCl_(2))rarr[CH_(2)=CH] overset("tautomerisation")rarr underset("Ethanal")(CH_(3)CHO)),(" |"),(" "CH_(2)-OH):}` |
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| 36. |
Glycerol changes to acrolein in the presence ofA. Conc. `H_(2)SO_(4)`B. Anhy. `ZnCl_(2)`C. `KHSO_(4)`D. Anhy. `CaCl_(2)` |
| Answer» Correct Answer - A::B::C | |
| 37. |
Glycerol on treatment with oxalic acid at `110^(@)C` formsA. Formic acidB. Allyl alcoholC. `CO_(2)` and `CO`D. Acrolein |
| Answer» Correct Answer - A | |
| 38. |
Arrange the following compounds in increasing order of acidic strength : p-nitrophenol, ethanol, phenol |
| Answer» ethanol, phenol, p-nitrophenol. | |
| 39. |
Glycerol is highyl viscous. It is due to the fact thatA. it is highly polarB. it contains three `-OH` groupsC. it forms intramolecular H-bondsD. it forms extensive intermolecular H-bonds |
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Answer» Correct Answer - D High viscosity of glycerol is attributed to extensive H-bonding. |
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| 40. |
When ethane-1, 2-diol is added to water, which of the following is observed ?A. The following of water increasesB. Water evaporature of water increasesC. Freezing point water is loweredD. The viscosity of water decreases |
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Answer» Correct Answer - C Due to extensive intermolecular H-Bonding, ethlene glycol is non-volatile. Adding a non-volatile solute (ethlyene glycol) to water lowers its freezing point. |
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| 41. |
When 1-butanol is heated with an excess of conc. Sulphuric acid, the main product isA. 1-ButeneB. 2-ButeneC. 2-Methyl-1-propanolD. 2-Methyl-1-butene |
| Answer» Correct Answer - B | |
| 42. |
Arrange the following compounds in increasing of order of their acidic strength 4-Nitrophenol, Phenol, 2, 4, 6-trinitrophenol. |
| Answer» Phenol `lt` 4- Nitrophenol `lt` 2, 4, 6-trinitrophenol. | |
| 43. |
What happens when : (i) Ethanol is treated with sodium ? (ii) Ethanol is heated with conc. `H_(2)SO_(4)` at `443 K` ? |
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Answer» (i) Sodium ethoxide is formed. (ii) Ethene is formed. |
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| 44. |
Which of the following is dihydric alcohol?A. GlycerolB. Propylene glycolC. CatecholD. Resorcinol |
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Answer» Correct Answer - B `CH_(3)-CHOHCH_(2)OH` |
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| 45. |
How will you convert methanol into ethanoic acid ? |
| Answer» `underset("Methanol")(CH_(3)OH) overset(P//I_(2))(rarr) CH_(3)I overset(KCN)(rarr) CH_(3)-C equiv N overset(H_(2)O //H^(+))(rarr) underset("Ethanoic acid")(CH_(3)COOH)` | |
| 46. |
`2ClCH_(2)CH_(2)OH("excess") underset(415K)overset(Conc. H_(2)SO_(4))rarr X underset("Fuse")overset(KOH)rarr Y` The compound Y isA. Ethylene glycolB. EthanolC. Divinyl etherD. Vinyl chloride |
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Answer» Correct Answer - C `2ClCH_(2)CH_(2)OH ("excess") underset(Delta//4.15 K)overset(Conc. H_(2)SO_(4))rarr ClCH_(2)underset((X))(CH_(2)-)O-CH_(2)CH_(2)Cl overset(KOH//"Fuse")rarr underset("Divinyl ether (Y)")(CH_(2)=CH-O-CH=CH_(2))` |
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| 47. |
Phenols can be converted into salicylic acid usingA. `C Cl_(4)` and alkali at 340 KB. `CO_(2)` and alkali under pressureC. `HCOOH` and conc. `H_(2)SO_(4)`D. `CHCl_(3)` and alkali at 340 K. |
| Answer» Correct Answer - A::B | |
| 48. |
Saponification of an oil results in the formation ofA. GlycolB. GlycerolC. Sodium salt of an acidD. Glycerol and soap |
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Answer» Correct Answer - D Glycerol and soap |
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| 49. |
Which of the following compound is known as oil of winter gree ?A. Phenyl benzoateB. Phenyl salicylateC. Phenyl acetateD. Methyl salicylate |
| Answer» Correct Answer - D | |
| 50. |
Which of the following compound decolourises bromine water also reacts with `PCl_(5)` to give white fumes of `HCl`?A. `CH_(3)CH_(2)OH`B. `CH_(3)-CH=CH-CH_(2)OH`C. `CH_(3)OCH_(2)CH=CH_(2)`D. both (B) and (C ) |
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Answer» Correct Answer - B `H_(3)C-CH=CH_(2)-OH underset(("Red"))overset(Br_(2)//C Cl_(4))rarr H_(3)C-underset(("Colourless"))(underset(Br)underset(|)(CH)-underset(Br)underset(|)(CH))-CH_(2)-OH` `H_(3)C-CH=CH-CH_(2)OH overset(PCl_(5))rarr HCl+POCl_(3)+H_(3)C-CH=CH-CH_(2)-Cl` |
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