Isomerism

Question 1

How many isomers are there for C4H10, C5H12, C6H14 and C7H16?

Answer 1

2, 3, 5 and 9

Question 2

Chain Isomerism

Answer 2

Compounds having the same molecular formula but different selection of principal carbon chain

Question 3

Position Isomerism

Answer 3

Compounds having same molecular formula but different position of the functional group, substituent or multiple bond

Question 4

Functional Isomerism

Answer 4

Compounds having the same molecular formula but different types of functional groups are present

Question 5

Metamerism

Answer 5

Different numbers of carbon atoms present bivalent atom or the functional group present in them

Question 6

Tautomerism

Answer 6

Special case of functional isomerism that are in dynamic equilibrium with each other

Question 7

Conformers

Answer 7

Compounds that are obtained when a molecule is rotated along C-C bond

Question 8

Staggered and Eclipsed form of ethane

Answer 8

Staggered, dihedral angle is 60 degree and eclipse, dihedral angle is 0 degree.

Question 9

Skew conformers

Answer 9

All conformers of C2H6 except for staggered and eclipsed form

Question 10

Stability of conformers of n-Butane

Answer 10

Anti-staggered(180)> Gauche(60)> Partially Eclipsed(120)>Fully eclipsed(0)

Question 11

Steric and Torosional Strain

Answer 11

Repulsion due to bulky group and repulsion between the bond pair

Question 12

Stability of conformers of cyclo-hexane

Answer 12

Chair> Twist Boat> Boat> Half Chair

Question 13

Stereoisomers

Answer 13

Compounds having the same molecular formula, but different orientation of atoms in space

Question 14

Optical Isomers

Answer 14

Compounds having same molecular formula, but they differ from each other based on optical rotation or optical activity

Question 15

Optical Activity

Answer 15

Compounds having same molecular formula, but one of them is dextrorotatory and another one is levorotatory

Question 16

Conditions for a compound to be chiral atom

Answer 16

1. It must be sp2 hybridise
2. All four valencies must be satisfied by different atoms on group

Question 17

Conditions for asymmetric and desymmetric molecules

Answer 17

POS, COS are absent

Question 18

Condition for opitcal isomerism

Answer 18

A compound must be dissymmetric to exhibit optical isomerism
Object and its mirror image should be non-super imposable of each other.

Question 19

Allene

Answer 19

Compounds having even number of consecutive double bonds

Question 20

Cumelenes

Answer 20

Compounds containing odd number of consecutive double bonds and they do not exhibit optical isomerism

Question 21

Racemic mixture

Answer 21

Equi-molar mixture of object and its mirror image

Question 22

Enantiomers

Answer 22

Objects and their non-superimposable mirror images are enantiomers to each other.
They have same physical properties.

Question 23

Meso Form

Answer 23

Form of optically active substance which will have POS and COS in it. They should be optically inactive.

Question 24

R and S configuration

Answer 24

When lowest priority is on vertical line, then clockwise is R form and anti-clockwise is S-form
When lowest priority is on horizontal line, then clockwise is S-form and anti-clockwise is R-form.

Question 25

Total optical isomers if the compound is unsymmetrical having ‘n’ chiral centre

Answer 25

2^n

Question 26

Stereogenic Area

Answer 26

Part of the molecule which shows stereoisomerism is known as the stereogenic area.

Question 27

D and L form

Answer 27

If the principal functional group is on the top and the hydroxyl group w.r.t last chiral is present on the right side of the plane, then it is D-form and if it is present on the left, then it is L-form.

Question 28

E and Z form

Answer 28

When the priority due to CIP rule is on the same side, then it is Z form and on the opposite side, then it is E form.

Question 29

If the symmetry is present, then geometrical isomerism is

Answer 29

2^n