1. How many optical isomers are possible in a compound with one chiral carbon?
a) 5
b) 4
c) 2
d) 3
Explanation: A compound with one chiral carbon has three optical isomers (+), (-) and (±).
2. Which of the following compound would show optical isomerism?
a) CH3 – CH(OH) COOH
b) H2N CH(CH3)2
c) (CH3)2 CHCHO
d) H2N CH2 COOH
Explanation: CH3 – CH(OH) COOH will show optical isomerism as it possess chiral carbon.
3. The number of configurational isomers of molecules having (n) different chiral carbons is ____________
a) 2n
b) 2n
c) 2n-1
d) 2n+1
Explanation: The number of configurational isomers of molecules having (n) different chiral carbons is 2n. It is calculated mathematically.
4. The number of racemic forms of molecules having (n) different chiral carbons is ____________
a) 2n
b) 2n
c) 2n-1
d) 2n+1
Explanation: The number of racemic forms of molecules having (n) different chiral carbons is 2n-1 whereas the number of configurational isomers of molecules having (n) different chiral carbons is 2n.
5. For a molecule with two like chiral carbon atoms, the number of optically inactive form is?
a) 1
b) 2
c) 3
d) 4
Explanation: For a molecule with two like chiral carbon atoms, the number of optically inactive form is one. This is always used for the calculation of optically inactive forms.
6. For a molecule with two like chiral carbon atoms, the number of optically active form is?
a) 4
b) 3
c) 1
d) 2
Explanation: For a molecule with two like chiral carbon atoms, the number of optically active form is two. This is always used for the calculation of optically active forms.
7. Find the number of stereoisomers for CH3 – CHOH – CH = CH – CH3.
a) 1
b) 2
c) 3
d) 4
Explanation: The number of stereoisomers for CH3 – CHOH – CH = CH – CH3 is four. This is calculated by the formula 2n+1.
8. The necessary condition for showing optical activity is the chirality of a molecule as a whole.
a) True
b) False
Explanation: The necessary condition for showing optical activity is the chirality of a molecule as a whole. It is the most important condition for showing optical activity.
9. The sufficient condition for showing optical activity is _______________
a) Molecule should have measurable amount of optical activity only
b) Polarimeter should have capacity of recording low-degree optical activity only
c) Chirality of molecule as a whole only
d) Both, the molecule should have measurable amount of optical activity and polarimeter should have capacity of recording low-degree optical activity
Explanation: The molecule should have measurable amount of optical activity and polarimeter should have capacity of recording low-degree optical activity.
10. Which of the following is an example of optically active compounds without chirality?
a) Tartaric acid
b) Sulfhonium salt
c) Diphenic acid
d) Glyceraldehyde
Explanation: Sulphhonium salt is an example of optically active compounds without chirality. It is a special case. There are various such molecules which are optically active compounds without chirality.