Which of the following compounds exhibits optical isomerism?
Answer: B
2-bromobutane has a chiral center (C2 with four different groups: Br, H, CH3, and C2H5), exhibiting optical isomerism. Other options lack a true chiral center.
Q.2Easy
The IUPAC name of (CH3)3C-CH2-OH is:
Answer: B
The structure has 5 carbons with main chain having OH at position 1 and two methyl groups at position 2. IUPAC name is 2,2-dimethyl-1-propanol.
Q.3Easy
Which reagent is used to distinguish between primary and secondary alcohols?
Answer: B
Lucas reagent (HCl + ZnCl2) forms turbidity with primary alcohols immediately, secondary alcohols after 5 minutes, and tertiary alcohols instantly with dehydration.
Q.4Easy
The most stable conformation of ethane is:
Answer: B
In staggered conformation, bonds are maximally separated reducing electron-electron repulsion and torsional strain. Staggered is most stable with ~12 kJ/mol lower energy than eclipsed.
Q.5Easy
Which set of reagents can convert benzene to toluene in one step?
Answer: A
Friedel-Crafts alkylation using CH3Cl with AlCl3 as Lewis acid catalyst converts benzene to toluene. This is the standard industrial method for alkylbenzene synthesis.
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Q.6Easy
In the nitration of toluene, the ortho and para isomers are major products because the methyl group is:
Answer: B
The methyl group is electron-donating through inductive and hyperconjugative effects, making the benzene ring more electron-rich. This activates the ring for EAS and directs incoming electrophiles to ortho and para positions.
Q.7Easy
Which of the following alkyl halides will give the fastest SN2 reaction with KOH in aqueous ethanol?
Answer: D
SN2 reactions proceed fastest with primary alkyl halides due to minimal steric hindrance around the carbon bearing the leaving group. CH3CH2Br (primary) > CH3CHBrCH3 (secondary) > (CH3)3CBr (tertiary).
Q.8Easy
In the oxidation of primary alcohols using PCC (pyridinium chlorochromate), the primary alcohol is converted to:
Answer: B
PCC is a mild oxidizing agent that oxidizes primary alcohols to aldehydes without further oxidation to carboxylic acids (unlike acidic KMnO4 or K2Cr2O7).
Q.9Easy
The coupling constant (J) in 1H-NMR for vicinal coupling (3J) typically ranges from:
Answer: B
Vicinal coupling (3J) between protons separated by 3 bonds typically has values of 6-18 Hz, with typical values around 7-8 Hz for anti-periplanar and 2-5 Hz for gauche conformations.
Q.10Easy
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.11Easy
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.12Easy
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.13Easy
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.14Easy
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.
Q.15Easy
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.16Easy
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.17Easy
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.18Easy
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.19Easy
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.20Easy
Which of the following compounds undergoes SN1 reaction most readily?
Answer: A
Tertiary alkyl halides form stable tertiary carbocations, making SN1 mechanism favorable.
