Question

The melting point of fatty acids in plant derived oils is influenced by:

• A. length and degree of unsaturation of hydrocarbon chain
• B. degree of unsaturation only
• C. length of hydrocarbon chain only
• D. Number of side and branch chains present

Hint:

Longer chain = Higher MP. More double bonds = Lower MP.

Answer 1

The Correct Option is A

Step 1: Concept
The physical properties of lipids, such as melting point, are determined by the structural characteristics of their fatty acid tails.

Step 2: Meaning
"Unsaturation" refers to the presence of double bonds, while "length" refers to the number of carbon atoms.

Step 3: Analysis
1. Chain Length: Longer chains have more van der Waals interactions, increasing the melting point. 2. Unsaturation: Double bonds (usually *cis* in plants) create kinks that prevent tight packing, drastically lowering the melting point. Both factors determine if an oil remains liquid at room temperature.

Step 4: Conclusion
Melting point is a function of both the length of the chain and the number of double bonds it contains. Final Answer: (A)