Conformational Analysis - 1 - Free MCQ Practice Test with solutions, NEET

The correct answer is Option C.
From the image we can see that 3 isomers are possible for pentane.

The correct answer is option D
Cyclopropane is a cycloalkane molecule with the molecular formula C₃H₆, consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms resulting in D₃H molecular symmetry. The small size of the ring creates substantial ring strain in the structure.

The correct answer is Option B.

The C-C-C bond angles in cyclopropane (60^o) and cyclobutane (90^o) are much different than the ideal bond angle of 109.5^o.This bond angle causes cyclopropane and cyclobutane to have a high ring strain. However, molecules, such as cyclohexane and cyclopentane, would have a much lower ring strain because the bond angle between the carbons is much closer to 109.5^o.

Correct answer is option D

Chair >Twist boat > Boat > Half-chair 

above is the stability order of
the conformed.
Stability is inversely proportional to potential energy.

The correct answer is Option D.
Although conformers differ in potential energy and stability, the difference is so small that it does not allow their practical separation.

Option C is correct.

The gauche conformer of 1,2-dichloroethane is lower in energy (more stable) than some other conformations and is polar, whereas the anti conformer has opposing C-Cl dipoles and is effectively non-polar (net dipole ≈ 0).

As temperature increases, the population of the higher-energy anti conformer increases. Because the anti conformer is less polar than the gauche conformer, the average (measured) dipole moment of a sample decreases with increasing temperature.

Option A is incorrect because eclipsed conformations are generally of higher potential energy than staggered (gauche or anti) conformations; a specific eclipsed form with H-Cl eclipsing is not lower than a staggered gauche form.

Option B is incorrect because the syn-periplanar (eclipsed) conformation is high in energy and therefore not the most stable.

Option D is incorrect: the two gauche rotamers of 1,2-dichloroethane are not true enantiomers. Each carbon bears two identical hydrogen atoms, and the two gauche forms are related by a proper rotation and are superposable; they do not constitute optically active enantiomers.

The correct answer is option A.

The correct answer is option D

This molecule is non-polar two Cl atoms in one carbon atom cancel the polarity other two Cl atoms on the next carbon.
Also all the Cl atoms are at max distance from each other so max. Stability due to less repulsion between Cl atoms. Dihedral angle between H and Cl is 60°

The Fischer Projections represent different types of stereoisomers. Here’s a breakdown of their relationships:

• Enantiomers: These are mirror images of each other and are not superimposable.
• Conformers: These are different spatial orientations of the same molecule, resulting from rotation around single bonds.
• Diastereomers: These are stereoisomers that are not mirror images of one another. They have different physical properties.
• Structural Isomers: These differ in the connectivity of their atoms, leading to different compounds.

The correct relationship for the given Fischer Projections is diastereomers.