O.P Tandon Test: Some Basic Principles - NEET MCQ

• Chain isomerism occurs due to the possibility of branching in carbon chains.
• Geometrical isomerism or configurational isomerism or cis-trans isomerism arises when the functional group are present on same side of carbon or are on opposite side of the carbon chain.
• Metamerism arises when organic compounds have the same molecular formula but different alkyl groups on either side of the functional group.
• In C₂H₅OC₂H₅ and CH₃OCH₂CH₂CH₃  , we can see that in diethyl ether we have 2 carbon atoms on the left side of oxygen but in methyl propyl ether we have one carbon atom on the left of oxygen. On the right hand side of oxygen, we have 2 carbon atoms but in methyl propyl ether, we have 3 carbon atoms.

So, we can say that above molecules are metamers. Therefore, option C is correct.

4 aromatic isomers are possible.

For positional isomerism in alkene 4C-atom required →

For geometrical isomerism in alkene also 4c–atom required →

There are 3 different positions of hydrogen. Hence, 3 structural isomers are possible.

• Partition chromatography because the substances are partitioned or distributed between liquid phases. 
• The two phases are water held in pores of the filter paper and the other phase is a mobile phase that passes through the paper.

Cis-trans Isomers:- It is under the class of geometric isomer,

• It exists in alkenes (organic molecules which have double bonds). 
• When two similar or higher priority groups are attached to the carbon on the same side, it is termed as cis isomer and when it is attached to the opposite side it is called a trans isomer.

Stability order ⇒ Gauche > Anti > Eclipse

Four primary amines are possible with the molecular formula C₄H₁₁N.

In CH₃ - CH₂ - Cl, the carbon marked with asterisk has the greatest positive charge due to high electronegativity of Cl.

(1) Vertical plane (2) Horizontal plane (3) Molecular Plane

Geometrical Isomers can be Diastereomers or Enantiomers.


Because geometrical isomers are around restricted rotation which can not be rotate or interconvertable.

• Phenol is C₆​H5​(OH) while benzyl alcohol is C₆H₅​(CH₂​OH). 
• Here there is a difference of −HC2​ between their molecular formula.
• According to the definition of homologous series, the adjacent members of the series differ by −CH₂​ group.
• Thus Phenol and benzyl alcohol are homologous of each other.

Number of chiral centers = 2

(B) & (C) compounds are R-configuration.

All four substituent are different so it is chiral compound.

Asymmetric = 2³ = 8

1-Heptanol & 4-Heptanol are not chiral
2-Heptanol & 3-Heptanol are chiral compound.

Stereoisomer differ from each other in configuration.

(2s, 3s) -2-chloro-3-Hydroxy Pentane

The above compounds are different in structure.

Twisted Boat form is chiral & optically active.

The correct answer is 3.

Geometrical isomerism arises in compounds that have restricted rotation around a double bond or a cyclic structure. This leads to the formation of isomers that differ in the spatial orientation of the substituents around the double bond or within the ring.

For example, consider a compound with the formula C3H6. This could refer to either propene or cyclopropane. Propene has a double bond and can exhibit geometrical isomerism, while cyclopropane has no double bonds and cannot exhibit geometrical isomerism.

Therefore, to exhibit geometrical isomerism, a compound must have a double bond or a cyclic structure with at least three carbon atoms. So, the minimum number of carbon atoms required for a compound to show geometrical isomerism is 3.

Alkenes like 1-hexene when flipped from top to bottom they have identical structures and also they have C=CH₂ unit which does not exist as cis-trans isomers.