Chemistry #expch001 Important Questions
Ch. 09. Functional Groups Containing Oxygen #expch_009
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- Which one of the following is also known as the lactic acid?
(a) 3-Hydroxy propanoic acid
(b) 2-Hydroxy propanoic acid
(c) 2-hydroxy butanoic acid
(d) 3-hydroxy butanoic acid
Answer (b)
Video Explanation
- Dehydration of alcohol is an example of
(a) addition reaction
(b) elimination reaction
(c) substitution reaction
(d) redox reaction
Answer: (b)
Explanation
Dehydration of alcohol is an example β-elimination. It involves the lose of two atoms/groups from adjacent carbon atoms.
Video Explanation
- Water gas heated at 450°C and 200 atm pressure in the presence of ZnO+Cr2O3 will produce
(a) Methanol
(b) Methanal
(c) Carbonic acid
(d) Methane
Answer: (a)
Explanation
Methanol is prepared on an industrial scale from a mixture of CO and H2. The mixture is subjected to 200atm pressure and passed over ZnO and Cr2O3 catalyst at 400 to 450 degrees celsius.
673k,300atm,/Cr2O3−ZnO
(CO+H2)+H2 CH3OH
Video Explanation
- The rectified spirit contains
(a) 12% alcohol
(b) 90% alcohol
(c) 95% alcohol
(d) 100% alcohol
Answer: (c)
Video Explanation
- When acetamide is treated with HNO2, the gas is evolved which of the following?
(a) H2
(b) O2
(c) N2
(d) CH4
Answer: (c)
Explanation
When acetamide is treated with HNO2, the gas is evolved in nitrogen gas. CH3 – CO – NH2 + HNO2 → CH3COOH + N2↑ + H2O
Acetamide Acetic acid
Video Explanation
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- By refluxing unsubstituted amide with acid, it will yield which of the following product(s)?
(a) ammonia
(b) carboxylic acid
(c) nitrogen gas
(d) both a b
Answer: (d)
Video Explanation
- Ethyl amine on acetylation gives which of the following?
(a) N-ethyl acetamide
(b) Acetamide
(c) Methyl acetamide
(d) N,N-dimethyl acetamide
Answer: (a)
Explanation
Ethyl amine on acetylation gives N-ethyl acetamide, as shown in given reaction.CH3CH2NH2 + CH3COCl → CH3CH2NHCOCH3 + HCl
Video Explanation
- Benzamide on reaction with POCl3 gives which of the following?
(a) Aniline
(b) Chlorobenzene
(c) Benzyl amine
(d) Benzonitrile
Answer: (d)
Explanation
POCl3 is a dehydrating agent so Benzamide on reaction with POCl3 gives benzonitrile.
Video Explanation
- The alcohol which does not react with Lucas reagent is
(a) sec butyl alcohol
(b) n-butanol
(c) tert-butyl alcohol
(d) iso-butyl alcohol
Answer: (d)
Explanation
Lucas test
is used to differentiate and categorize primary, secondary and tertiary alcohols using a solution of anhydrous zinc chloride in concentrated hydrochloric acid. This solution is commonly referred to as the Lucas reagent. The reaction that occurs in the Lucas test can be seen as a nucleophilic substitution reaction.
The reaction displays the difference in reactivity of the different types of alcohol as well as the difference in the ease at which corresponding carbocations of the alcohols are formed. For example, primary alcohols do not react readily at room temperature with the added Lucas reagent whereas tertiary alcohols react immediately.
Isobutyl alcohol does not give a Lucas reagent test.
Video Explanation
- Which of the following is formed when glycerol is heated with oxalic acid at 503K?
(b) Acrolein
(c) Allyl alcohol
(d) Methanoic acid
Answer: (c)
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- An ether is more volatile than an alcohol having the same molecular formula. What is the reason for this difference?
(a) dipolar character of ethers
(b) alcohols having resonance structures
(c) inter-molecular hydrogen bonding in ethers
(d) inter-molecular hydrogen bonding in alcohols
Answer: (d)
Explanation
The ether are more volatile than alcohol of same molecular mass because in alcohols there is intermolecular H-bonding which makes it less volatile and High B.P. But in case of ether there is no intermolecular H-Bonding which makes it more volatile and less B.P.
Video Explanation
- Ethers may be used as solvents because they react only with which of the following reactants?
(a) Acids
(b) Bases
(c) Oxidising agent
(d) none of these
Answer: (a)
Explanation
Ethers resist the attack of nucleophiles and bases. However, they are very good solvents in many organic reactions due to their ability to solvate cations by donating the electron pair from oxygen atom. Ethers are generally less reactive and react only with acids.
Video Explanation
- What are the products when ethyl isopropyl ether is cleaved with concentrated HI?
(a) ethanol and 2-iodo-2-methylpropane
(b) ethanol and 2-methylpropane
(c) iodoethane and isopropyl alcohol
(d) none of these
Answer: (c)
Explanation
Ether + HX → Alkyl halide + Alcohol
Halide attacks at less hindered site to produce alkyl halide. So,
Ethyl isopropyl ether + HI/Heat/Water → Isopropyl alcohol + Iodoethane.
Video Explanation
- Which of the following has the most acidic hydrogen?
(a) hexane-2,4-dione
(b) hexane-2,3-dione
(c) hexane-2,5-dione
(d) hexane-3-one
Answer: (a)
Explanation
2,4 Hexanedione has most acidic hydrogen this is because the Carbanion left after the removal of H+ is resonance.
Video Explanation
- A new C-C bond formation is possible in
(a) cannizzaro reaction
(b) friedel crafts reaction
(c) clemmensen reduction
(d) none of these
Answer: (b)
Video Explanation
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- A mixture of benzaldehyde and formaldehyde on heating with aqueous NaOH solution gives
(a) benzyl alcohol + sodium formate
(b) sodium benzoate + methanol
(c) benzyl alcohol + methanol
(d) sodium benzoate + sodium formate
Answer: (a)
Video Explanation
- The formation of cyanohydrin from a ketone is an example of
(a) electrophilic addition
(b) nucleophilic addition
(c) nucleophilic substitution
(d) none of these
Answer: (b)
Video Explanation
- The reaction of ethyl formate with an excess of CH3MgI followed by hydrolysis gives
(a) Methanol
(b) n-propyl alcohol
(c) propanal
(d) isopropyl alcohol
Answer: (d)
Video Explanation
- Benzoic acid reacts with conc.HNO3 and conc.H2SO4 to give
(a) o,p-nitrobenzoic acid
(b) p-nitrobenzoic acid
(c) m-nitrobenzoic acid
(d) none of these
Answer: (c)
Video Explanation
- Formic acid and acetic acid are distinguished by reaction with
(a) sodium ethoxide
(b) HgCl2
(c) sodium
(d) 2,4-dinitrophenylhydrazine
Answer: (b)
Explanation
mercury(II)chloride is a white solid. Mercuric chloride exists not as salt composed of discrete ions, but rather consists of linear triatomic molecules, hence its tendency to sublime. Mercuric chloride is also a chemical reagent used in organic synthesis and analytical chemistry.
Corrosive sublimate (HgCl2) reaction with formic acid to give calomel (mercurous chloride, mercury (II)chloride), Hg2Cl2 , hydrochloric acid and liberation of carbon dioxide. The chemical reaction is, HCOOH+2HgCl2→2Hg2Cl2↓+2HCl+CO2↑HCOOH+2HgCl2→2Hg2Cl2↓+2HCl+CO2↑
HgCl2 (Mercury(II)chloride) is obtained as white precipitate in the above chemical reaction and formic acid acts as a reducing agent, reduces mercury (II)(II) chloride to mercury (I)(I) chloride.
But acetic acid is not affected, when reaction with corrosive sublimate (HgCl2) and it does not show any reducing property. Corrosive sublimate (HgCl2) can be used to distinguish between formic acid and acetic acid.
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