1. Choose the incorrect option regarding Isomerism:
- 1) Geometric and optical isomerism are two types of Stereo Isomerism
- 2) There are two types of Isomerism : Structural and Stereo Isomerism
- 3) They have the different molecular formula
- 4) They differ in both physical and chemical properties
Answer: 3)
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)
- 1) Optical Isomerism
- 2) Geometrical Isomerism
- 3) Stereo Isomerism
- 4) Structural Isomerism
Answer: 2)
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
Answer: 1)
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
- 1) It is a single compound
- 2) It can be separated into optically active enantiometric pairs
- 3) The molecules of the meso isomers are chiral
- 4) Meso form is optically inactive due to external compensation
Answer: 1)
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
- 1) 4-hexene
- 2) 3-hexene
- 3) 2-hexene
- 4) 1-hexene
Answer: 4)
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?
- 1) aldehyde
- 2) alkene
- 3) alkyne
- 4) alkane
Answer: 2)
Explanation: In elimination reaction, when protic acids react with alcohol, they lose water molecule to form alkenes.
7. A fat on hydrolysis would yield?
- 1) Only soap
- 2) Ethanol and glycerol
- 3) Ethanol and soap
- 4) Glycerol and soap
Answer: 4)
Explanation: During saponification process, fat on hydrolysis will yield glycerol and soap.
8. Which among the following correctly defines Diastereomer?
- 1) Separation is very difficult
- 2) These differ in all physical properties
- 3) Nonsuperimposable object mirror relationship
- 4) These have same magnitude but different signs of optical rotation
Answer: 2)
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?
Answer: 2)
Explanation: n-pentane, 2-ethylpropane, and 2-methylbutane are the 3 isomeric alkanes of C₅H₁₂ (pentane).
10. Identify the chiral molecule among the following:
- 1) Isobutyl alcohol
- 2) 1-bromo 3-butene
- 3) 2-pentanol
- 4) Isopropyl alcohol
Answer: 1)
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.
