Match List-I with List-II
List-I List-II Molecules Most Reactive towards (A). Ethyl bromide (I). $S_N1$ (B). Tertiary butyl bromide (II).$S_N2$ (C). Acetone (III). Electrophilic substitution (D). Benzene (IV). Nucleophilic addition
Choose the correct answer from the options given below:
Chemical Reactivity Matching Explained
This question requires matching different types of organic molecules with their characteristic modes of reactivity. Let's analyze the reactivity of each molecule listed in List-I:
Analyzing Reactivity of Molecules
- (A) Ethyl bromide: This is a primary alkyl halide. Primary alkyl halides like ethyl bromide ($CH_3CH_2Br$) are prone to $S_N2$ reactions. This is because the carbon atom attached to the bromine is relatively unhindered, allowing a nucleophile to attack from the back side. The formation of a primary carbocation needed for $S_N1$ is energetically unfavorable.
- (B) Tertiary butyl bromide: This is a tertiary alkyl halide ($(CH_3)_3CBr$). Tertiary alkyl halides readily undergo $S_N1$ reactions. This is due to the stability of the tertiary carbocation intermediate formed upon the departure of the leaving group (bromide ion). The carbocation is stabilized by the electron-donating effect of the three methyl groups.
- (C) Acetone: Acetone ($CH_3COCH_3$) is a ketone, containing a carbonyl group ($C=O$). The carbon atom in the carbonyl group is partially positive (electrophilic) due to the electronegativity of the oxygen atom. This makes it susceptible to attack by nucleophiles, leading to Nucleophilic addition reactions.
- (D) Benzene: Benzene ($C_6H_6$) is an aromatic compound. Aromatic systems are characterized by their stability due to delocalized pi electrons. While addition reactions are possible, they disrupt the aromaticity. Benzene preferentially undergoes Electrophilic substitution reactions, where an electrophile replaces a hydrogen atom on the ring, maintaining the stable aromatic system.
Summary of Matches
Based on the analysis, the correct matches are:
(A) Ethyl bromide is most reactive towards $S_N2$ (II).
(B) Tertiary butyl bromide is most reactive towards $S_N1$ (I).
(C) Acetone is most reactive towards Nucleophilic addition (IV).
(D) Benzene is most reactive towards Electrophilic substitution (III).
This corresponds to the combination (A) - (II), (B) - (I), (C) - (IV), (D) - (III).
| List-I Molecule | List-II Reactivity Type | Reason |
| (A) Ethyl bromide | (II) $S_N2$ | Primary structure, low steric hindrance for backside attack. |
| (B) Tertiary butyl bromide | (I) $S_N1$ | Tertiary structure, stable tertiary carbocation intermediate. |
| (C) Acetone | (IV) Nucleophilic addition | Electrophilic carbonyl carbon ($C=O$) attacked by nucleophiles. |
| (D) Benzene | (III) Electrophilic substitution | Aromatic system stability maintained by substitution over addition. |
Important Questions from Chemistry (CUET PG) Mixed
- Which of the following atmospheric gas does not dissolve in water at standard temperature and pressure conditions?
- Which of the following physical processes is responsible for the blue color of the sky?
- Arrange the following coal types in the increasing order of their heat content (KJ/kg)
(A). Peat
(B). Lignite
(C). Anthracite
(D). Bituminous
(E) Sub-bituminous
Choose the correct answer from the options given below: - In which of the following layers of atmosphere, does the temperature decrease with the increase in height from the earth's surafce?
(A). Troposphere
(B). Mesosphere
(C). Thermosphere
(D). Stratosphere
Choose the correct answer from the options given below: Choose the correct statement from the following:
(A). Water has highest density at 4°C
(B). Freezing point of water is 0°C
(C) An Ice cube does not completely dip in water, rather floats on water in a glass.
(D). Addition of common salt reduces freezing point of water.
Choose the correct answer from the options given below:
