In the Williamson ether synthesis, the reactivity order for nucleophilic substitution by alkoxide ions (RO-) follows which pattern?
Answer: A
In Williamson ether synthesis, the alkoxide ion attacks via SN2 mechanism, which prefers primary alkyl halides due to less steric hindrance. Tertiary substrates don't react due to steric hindrance.
Q.42Easy
In the ozonolysis of 2-methylbut-2-ene, the number of organic products formed is:
Answer: B
2-methylbut-2-ene: (CH3)2C=CH-CH3. Ozonolysis cleaves the C=C to give (CH3)2C=O (acetone) and CH3-CHO (acetaldehyde). Two different organic products are formed.
Q.43Easy
The compound that will show geometrical isomerism is:
Answer: B
CH3-CH2-CH=CH-CH3 (pent-2-ene) shows geometrical isomerism because the C=C has two different groups on each carbon. Option (a) is butane with symmetric substituents; (c) has geminal methyls; (d) is hexene with symmetric groups.
Q.44Easy
In the polymer synthesis by condensation polymerization, the type of linkage formed when dicarboxylic acids react with diols is:
Answer: B
When dicarboxylic acids (HOOC-R-COOH) react with diols (HO-R'-OH), ester bonds form between the carboxyl and hydroxyl groups, creating polyester polymers with repeating ester linkages.
Q.45Easy
Which of the following compounds will undergo SN2 reaction most readily?
Answer: B
SN2 reaction requires easy access to the carbon bearing the leaving group. Ethyl bromide (primary alkyl halide) has minimal steric hindrance and is highly reactive in SN2 reactions.
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Q.46Easy
The IUPAC name of the compound with structure CH3-CH(OH)-CH2-CHO is:
Answer: B
The longest carbon chain contains 4 carbons with the aldehyde group (CHO) at position 1. The hydroxyl group is at position 3, giving 3-hydroxybutanal.
Q.47Easy
In the nitration of benzene using HNO3/H2SO4, the electrophile is:
Answer: B
H2SO4 protonates HNO3 to form H2NO3+, which loses water to generate the nitronium ion (NO2+), the actual electrophile in electrophilic aromatic substitution.
Q.48Easy
Which functional group shows a strong absorption around 1700-1750 cm⁻¹ in IR spectrum?
Answer: C
The C=O stretch of carbonyl compounds (aldehydes, ketones, carboxylic acids, esters) appears characteristically around 1700-1750 cm⁻¹ in IR spectrum.
Q.49Easy
Grignard reagent (RMgX) reacts with water to give:
Answer: C
Grignard reagents are strong nucleophiles and strong bases. They readily abstract a proton from water, producing an alkane (R-H) and magnesium halide salt.
Q.50Easy
In the Friedel-Crafts alkylation of benzene with alkyl halides, the catalyst used is:
Answer: B
AlCl3 is the standard Lewis acid catalyst for Friedel-Crafts alkylation. It activates the alkyl halide to form a carbocation, which then attacks the aromatic ring.
Q.51Easy
Which of the following compounds undergoes SN1 reaction most readily?
Answer: A
Tertiary alkyl halides form stable tertiary carbocations, making SN1 mechanism favorable.
Q.52Easy
Which reagent is used to differentiate between aldehydes and ketones?
Answer: C
Both Tollens and Fehling reagents give positive test with aldehydes (silver mirror and red precipitate respectively) but not with ketones.
Q.53Easy
The oxidation of primary alcohols with chromic acid (H2CrO4) in acidic medium gives:
Answer: C
Chromic acid oxidizes primary alcohols to carboxylic acids. The aldehyde is an intermediate which is further oxidized.
Q.54Easy
Which mechanism best describes the addition of HBr to propene?
Answer: C
Addition to alkenes follows electrophilic addition mechanism with carbocation formation, leading to Markovnikov's product.
Q.55Easy
Which of the following compounds exhibits keto-enol tautomerism?
Answer: B
Acetone (CH3-CO-CH3) has α-hydrogen atoms and can exist in equilibrium between keto and enol forms.
Q.56Easy
Which of the following is not a nucleophile?
Answer: C
NO2+ (nitronium ion) is an electrophile with positive charge, not a nucleophile. All others have lone pairs or negative charge.
Q.57Easy
The Williamson ether synthesis involves reaction of an alkoxide with:
Answer: B
Williamson ether synthesis uses SN2 reaction between alkoxide (R-O-) and alkyl halide (R'-X) to form R-O-R'.
Q.58Easy
Which of the following shows the most stable carbocation?
Answer: C
Tertiary carbocation (CH3)3C+ is most stable due to maximum hyperconjugation and inductive stabilization from three alkyl groups.
Q.59Easy
In the ozonolysis of but-2-ene, the products formed are:
Answer: A
But-2-ene (CH₃-CH=CH-CH₃) on ozonolysis gives two identical fragments, each being acetaldehyde (CH₃CHO). The double bond cleaves symmetrically.
Q.60Easy
Which mechanism is involved in the reaction of tert-butyl bromide with aqueous NaOH?
Answer: A
tert-Butyl bromide is a tertiary alkyl halide. Tertiary substrates preferentially undergo SN1 mechanism due to stable tertiary carbocation formation. SN2 is hindered by steric effects.
