This set of Organic Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Isomerism”.
1. Choose the incorrect option regarding Isomerism:
a) They differ in both physical and chemical properties
b) They have the different molecular formula
c) There are two types of Isomerism : Structural and Stereo Isomerism
d) Geometric and optical isomerism are two types of Stereo Isomerism
Explanation: Isomers are compounds that have same molecular formula.
2. Isomerism that arises out of the difference in spatial arrangement of atoms or groups about the doubly bonded carbon atoms are called? (In specific)
a) Structural Isomerism
b) Stereo Isomerism
c) Geometrical Isomerism
d) Optical Isomerism
Explanation: These geometrical isomers are not mirror images of each other and they differ in spatial arrangement from one another.
3. Isomers with similar groups on the same side are called as ” trans” isomers. State true or false
Explanation: “Trans” isomers are those with similar groups arranged in opposite direction. The Isomers with similar groups on the same side are called as “cis” isomers.
4. Which among the following defines Meso forms of isomers
a) Meso form is optically inactive due to external compensation
b) The molecules of the meso isomers are chiral
c) It can be separated into optically active enantiometric pairs
d) It is a single compound
Explanation: Meso forms of isomers are single compound and their molecules are achiral
and hence they cannot be separated into pairs.
5. Which among the following does not exhibit geometric isomerism
Explanation: 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.
6. Which among the following is formed when an alcohol is dehydrated?
Explanation: In elimination reaction, when protic acids react with alcohol, they lose water molecule to form alkenes.
7. A fat on hydrolysis would yield?
a) Glycerol and soap
b) Ethanol and soap
c) Ethanol and glycerol
d) Only soap
Explanation: During saponification process, fat on hydrolysis will yield glycerol and soap.
8. Which among the following correctly defines Diastereomer?
a) These have same magnitude but different signs of optical rotation
b) Nonsuperimposable object mirror relationship
c) These differ in all physical properties
d) Separation is very difficult
Explanation: Diastereomers differ in all physical properties. The rest of the points are related to Enantiomers.
9. The molecular formula C5H12 contains how many isomeric alkanes?
Explanation: n-pentane, 2-ethylpropane, and 2-methylbutane are the 3 isomeric alkanes of C5H12 (pentane).
10. Identify the chiral molecule among the following:
a) Isopropyl alcohol
c) 1-bromo 3-butene
d) Isobutyl alcohol
Explanation: Chirality is the condition for a molecule to be optically active and here isobutyl alcohol is the only compound is optically active and hence it is the chiral molecule.
Sanfoundry Global Education & Learning Series – Organic Chemistry.
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