Isomerism

No of asymmetric carbon atoms in
- dimethylcyclohexane
-methylcyclopentene
-methylcyclohexene

Tautomerism It is functional isomerism in -which the isomers are readily interchangeable and maintain a dynamic equilibrium with each other.

Step 1: Two C=C bonds are present.
Step 2: Each double bond shows E/Z isomerism. Total = 2² = 4

Step 1: Condition for chirality. Presence of asymmetric carbon is required.
Step 2: Checking option (1). No asymmetric carbon present.

Step 1: Nature of groups. –CN and –NC are different functional groups.
Step 2: Conclusion. Thus functional isomerism is shown.

Step 1: Analyze the compound's symmetry.
The compound contains two chiral centers (the carbon atoms attached to ), so it can have 4 enantiomers (two pairs of non-superimposable mirror images).
Step 2: Conclusion.
The number of enantiomers of the compound is 4. Final Answer:

Step 1: Possible isomers: - o-bromotoluene - m-bromotoluene - p-bromotoluene - benzyl bromide
Step 2: Benzyl bromide reacts readily with alcoholic AgNO₃ forming AgBr precipitate, whereas aryl bromides do not.

3-Methylhexane contains a chiral carbon with four different groups attached.

Meso compounds are characterized by an internal plane of symmetry that renders them achiral.

The compound has two similar asymmetric -atoms. It has plane of symmetry and exists in meso form.

Step 1: Meso compounds have plane of symmetry and chiral centres.
Step 2: 2,3-dichlorobutane has two chiral centres and a plane of symmetry.

Step 1: Optical isomerism requires a chiral carbon atom (attached to four different groups). Step 2: \beginitemize • 2,3-Dimethylpentane — has plane of symmetry ⟹ achiral • 2,2-Dimethylbutane — highly symmetrical ⟹ achiral • 3-Methylhexane — carbon at position 3 is attached to four different groups ⟹ chiral \enditemize Step 3: Hence, only 3-Methylhexane shows optical isomerism.

Step 1: Understanding the Concept:
We use the Cahn-Ingold-Prelog (CIP) priority rules to assign R/S configurations. In a Fischer projection, if the lowest priority group (H) is on a horizontal line, the observed configuration (CW for R, CCW for S) must be reversed.

Step 2: Detailed Explanation:
At Carbon 2 (C2): 1. Priority: . 2. Path from 1 2 3 is Clockwise (R). 3. Since H is horizontal, reverse R S. (Wait, let's re-verify priority: (1), (2), (3). 1 2 3 is CCW. Reverse R). At Carbon 3 (C3): 1. Priority: . 2. Path from 1 2 3 is Clockwise (R). 3. Since H is horizontal, reverse R S.

Step 3: Final Answer
The configuration is (2R, 3S).