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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.
| 251. |
At room temperature tertiary alcohols form white turbidity very fast with Lucas reagent while primary alcohols do not. Give reason. |
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Answer» A carbocation intermediate is formed when `HCl(g)` reacts with an alcohol in the presence of anhydrous `ZnCl_(2)` (dehydrating agent). Since tertiary carbocation is very stable while primary carbocation is rather unstable therefore, tertiary alcohols react very fast with Lucas reagent to form white turbidity immediately while the primary alcohols do not react at room temperature. `underset("Alcohol")(R-underset(..)overset(..)(O)-H)+H-Cl rarr underset(("Protonated"),("Alcohol"))(R-underset(H)underset(|)overset(o+)(O)-H) underset("Carbocation")(overset("Slow")(rarr)R^(+) underset("Fast")overset(Cl^(-))(rarr)) underset("Alkyl chloride")(R-Cl)` |
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| 252. |
Assertion : p-Nitrophenol is a stronger acid than p-cresol. Reason : `NO_(2)` group is an electron withdrawing group while `CH_(3)` group is electron releasing in nature.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 - A Reason is the correct explanation for assertion. |
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| 253. |
Assertion : `C_(2)H_(5)OH` is a weaker acid than phenol but is a stronger nucleophile than phenol. Reason : In phenol, lone pair of electrons on oxygen is directed towards the ring due to resonance.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 - A Reason is the correct explanation for assertion. |
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| 254. |
P-nitrophenol is a stronger acid than phenol while p-cresol is a weaker acid. Discuss. |
| Answer» The `-NO_(2)` group is an electron withdrawing group. When present at the para position in the ring, it decreases the electron density on the oxygen atom of `O-H` group due to conjugation and the release of `H^(+)` ion becomes easier than in phenol. On the other hand, `-CH_(3)` group is an electron releasing group. It increases the electron density on the oxygen atom and the release of `H^(+)` ion becomes difficult compared to phenol. therefore, p-nitrophenol is a stronger acid than phenol while p-cresol is a weaker acid. | |
| 255. |
When ethanol dissolves in water, which of the following is observed?A. Absorption of heat and decrease in volumeB. Absorption of heat and increase in volumeC. Emission of heat and increase in volumeD. Emission of heat and increase in volume |
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Answer» Correct Answer - B New inter-molecular forcess between `C_(2)H_(5)OH` and `H_(2)O` molecules are weaker than the the old intermolecular forces between `H_(2)O-H_(2)O` molecules and `C_(2)H_(5)OH-C_(2)H_(5)OH` molecules. As such `Delta H_(max)` and `Delta V_(mix)` are both positive. |
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| 256. |
The number of optically active isomers possible for the compound `CH_(3)-underset(OH)underset(|)(CH)-underset(OH)underset(|)(CH)-underset(OH)underset(|)(CH)-CH_(2)OH`A. 3B. 4C. 8D. 6 |
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Answer» Correct Answer - C The molecule is not symmetrical and there are three chiral carbon atoms i.e., `n = 3` `:.` The number of isomers `= 2^(n) = 2^(3) = 8`. |
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| 257. |
Sulphonation of phenol with conc. `H_(2)SO_(4)` at 288-293 K givesA. o-Phenolsulphonic acidB. Sulphonic acidC. p-Phenolsulphonic acidD. Sulphone |
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Answer» Correct Answer - A At lower temperature i.e., 288 K it gives ortho phenol sulphuric acid. |
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| 258. |
In `CH_(3)CH_(2)OH` the bond that undergoes heterolytic cleavage most readily is:A. `C-C`B. `C-O`C. `C-H`D. `O-H` |
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Answer» Correct Answer - D Electronegativties of C, H and O are `2.5, 2.1` and `3.5` respectively. The greatest electronagetivity difference is for `O-H` bond and as such it readily undergoes heterolytic cleavage most easily. |
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| 259. |
Phenol is more readily soluble inA. dil. HClB. Both NaOH and HClC. NaOH solD. Sodium bicarbonate solution |
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Answer» Correct Answer - C `C_(6)H_(5)OH+NaOH rarr C_(6)H_(5)ONa+H_(2)O` |
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| 260. |
Among the following the one that gives pistive idoform test upon reaction with `I_(2)` and `NaOH` is:A. `CH_(3)CH_(2)CH(OH) CH_(2)CH_(3)`B. `C_(6)H_(5)CH_(2)CH_(2)OH`C. `H_(3)C-underset(CH_(3))underset(|)(CH)-CH_(2)-OH`D. `PhCH(OH)CH_(3)` |
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Answer» Correct Answer - D `PhCH(OH)CH_(3)` upon oxidation will give `Ph-COCH_(3)`. Being a methyl ketone, it will give positive iodoform test. |
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| 261. |
Which of the following alcohols on oxidation gives a carboxylic acid with lesser number of carbon atoms ?A. `CH_(3)CH_(2)CH_(2)CHO`B. `CH_(3)CH_(2)CH_(2)OH`C. `(CH_(3))_(3)C.OH`D. `(CH_(3))_(3)C-CH_(2)-OH` |
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Answer» Correct Answer - C Secondary and tertiary alcohols on oxidation give carboxylic acids having lesser number of carbons. |
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| 262. |
The reaction between alcohol and carboxylic acids is calledA. EsterificationB. HydrolysisC. SaponificationD. Hydrogenation |
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Answer» Correct Answer - A It leads to formation of ester and therefore, called esterfication. |
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| 263. |
Organic acid without a carboxylic acid group isA. ascorbic acidB. vinegarC. Oxalic acidD. picric acid |
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Answer» Correct Answer - D Picric acid is a 2,4,6-trinitrophenol. |
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| 264. |
Aspirin is known asA. Phenyl salicylateB. Acetyl salicylateC. Methyl salicylic acidD. Acetyl salicylic acid |
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Answer» Correct Answer - D Aspirin is acetylsalicylic acid |
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| 265. |
Aspirin is known as :A. Acetyl salicylic acidB. Phenyl salicylateC. Acetyl salicylateD. Methyl salicylate acid |
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Answer» Correct Answer - A Aspirin is acetyl salicylic acid. |
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| 266. |
The compound which undergoes dehydration very easily is :A. 2-Methylpropan-2-olB. Ethyl alcoholC. 3-Methylbutan-2-olD. n-Propyl alcohol |
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Answer» Correct Answer - A `underset((A 3^(@) "alcohol"))underset("2-Methyl propan-2-ol") (CH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)(C)-CH_(3))` Being tertiary in nature, the alcohol undergoes dehydration most easily. |
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| 267. |
Phenol reacts with which of the following reagents to give salicyladehyde?A. `CH_(3)Cl_(3)+NaOH`B. `SiO_(2)+NaOH`C. `CHBr_(3)+KBrO_(3)`D. `KClO+HClO_(4)` |
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Answer» Correct Answer - A Choice (A) is the correct answer. The reaction is called Riemer Tiemann Reaction. |
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| 268. |
Phenol gives.......colour with neutral `FeCl_(3)` solutionA. violetB. greenC. Red `rarr` green `rarr` whiteD. blue |
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Answer» Correct Answer - A Violet colour due to the formation of `(C_(6)H_(5)O)_(3)Fe`. |
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| 269. |
Which one of the following compounds gives characteristic deep colour with `FeCl_(3)` solution ?A. acetoneB. ethanolC. phenolD. acetic acid |
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Answer» Correct Answer - C Phenol gives purple colour with `FeCl_(3)`. |
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| 270. |
Ortho -nitrophenol is less soluble in water than `p`-and `m-`nitrophenols becauseA. o-Nitrophenol is more steam volatile than m-and p- isomersB. o-Nitrophenol shows intramolecular H-bondingC. o-Nitrophenol shows intramolecular H-bondingD. Melting point of o-Nitrophenol is lower than those of m- and p-isomers. |
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Answer» Correct Answer - B Due to the presence of intramolecular hydrogen bonding, molecules of o-nitrophenol are not involved in any hydrogen bonding with the molecules of water whereas those of p-nitrophenol and m-nitrophenol exibit hydrogen bonding with water molecules.Therefore, o-nitrophenol is less soluble in water as compared to p- and m-isomers. |
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| 271. |
In the reaction of phenol with `CHCl_(3)` and aqueous `NaOH` at `70^(@)C` (343K), the electrophile attacking the ring is :A. `CHCl_(3)`B. `CHCl_(2)`C. `:C Cl_(2)`D. `COCl_(2)` |
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Answer» Correct Answer - C See mechanism of Reimer Tiemann reaction. |
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| 272. |
Which one/ones of the following reactions will yield 2-propanol ? Choose the right asnwer from (A), (B), (C) and (D) I. `CH_(2) = CH-CH_(3)+H_(2)O overset(H^(+))rarr` II. `CH_(3)-CHO underset((ii) H_(2)O)overset((i) CH_(3)MgI)rarr` III. `CH_(2)O underset((ii) H_(2)O)overset((i) C_(2)H_(5)MgI)rarr` IV. `CH_(3)=CH-CH_(3) overset("Neutral" KMnO_(4))rarr`A. I and IIB. II and IIIC. III and ID. II and IV |
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Answer» Correct Answer - A `HCHO (CH_(2)O)` with `C_(2)H_(5)MgI` will give a `1^(@)` alcohol and propene `(CH_(2)=CH-CH_(3))` with neutral `KMnO_(4)` will give a diol. Therefore correct answer is A (I and f II). `CH_(2)=CH-CH_(3)+H_(2)O underset("M.Rule")overset(H^(+))rarr CH_(3)-overset(OH)overset(|)(C)-CH_(3)` `CH_(3)-CHO underset((ii) H_(2)O //H^(+))overset((i) CH_(3)MgI)rarr CH_(3)-overset(OH)overset(|)(C)-CH_(3)`. |
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| 273. |
Which of the following reagents can not be used to distinguished between phenol and benzyl alcohol?A. `FeCl_(3)`B. `NaHCO_(3)`C. `Br_(2)//C Cl_(4)`D. `NaOH` |
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Answer» Correct Answer - B `NaHCO_(3)` is a very weak base and hence does not react with either of the two compounds. |
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| 274. |
Cyclohexene is best prepared from cyclohexanol by which of the followingA. Conc. `H_(3)PO_(4)`B. Conc. `HCl//ZnCl_(2)`C. Conc. `HCl`D. Conc. `HBr` |
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Answer» Correct Answer - A `HC-=CH underset(H_(2)SO_(4))overset(HgSO_(4))rarr CH_(3)CHO underset((ii) H_(2)O)overset((i)CH_(3)MgBr)rarr CH_(3)CHOHCH_(3)overset(Pbr_(3))rarr CH_(3)CHBrCH_(3)` |
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| 275. |
How will you convert ethyl amine to ethyl alcohol and vice versa ? |
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Answer» Ethyl amine to ethyl alcohol `underset("Ethyl amine")(C_(2)H_(5)NH_(2))+HONO overset((NaNO_(2)//HCl))(rarr) underset("Ethyl alcohol")(C_(2)H_(5)OH)+H_(2)O+N_(2)` Ethyl alcohol to ethyl amine `underset("Ethyl alcohol")(C_(2)H_(5)OH) overset(PCl_(5))(rarr) underset("Ethyl chloride")(C_(2)H_(5)Cl) overset(NH_(3) (alc.))(rarr) underset("Ethyl amine")(C_(2)H_(5)NH_(2))` |
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| 276. |
Choose the correct statement for the reaction A. (b) is formed more rapidly at higherB. (b) is more volatile than (a)C. (a) is more volatle than (b)D. (a) is formed in higher yields at lower temperature |
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Answer» Correct Answer - C (a) Undergoes intramolecular H-bonding. (b) Undergoes intermolecular H-bonding. |
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| 277. |
Na reacts with phenolA. `H_(2)` gasB. BenzeneC. `CO_(2)` gasD. CO gas |
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Answer» Correct Answer - A `C_(6)H_(5)OH+Na rarr C_(6)H_(5)ONa+1//2 H_(2)`. |
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| 278. |
A fruity smell is obtained by the reaction of ethanol withA. `PCl_(5)`B. `CH_(3)COCH_(3)`C. `CH_(3)COOH`D. None of these |
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Answer» Correct Answer - C Ethanol and `CH_(3)COOH` react to ester which has fruity smell. |
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| 279. |
Which of the following compound is obtained on passing ethanol vapours on heate `Al_(2)O_(3)` ?A. EthyletherB. AcetoneC. EthaneD. Ethanol |
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Answer» Correct Answer - A `2C_(2)H_(5)OH (g) overset(Al_(2)O_(3))rarr underset("Diethyl ether")(C_(2)H_(5)OC_(2)H_(5))` |
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