Question

Which of the following statements is/are correct with reference to composition of fats and oils;
(A). The chain length and degree of saturation control the properties that are found within the fatty acids and lipids
(B). Fatty acids typically contain an even number of carbon atoms.
(C). The saturated acids have higher melting points than unsaturated acids of corresponding size.
Choose the most appropriate answer from the options given below:

• A. (A) and (C) only
• B. (B) and (C) only
• C. (A) only (B) only
• D. (A), (B) and (C)

Hint:

Remember these key fatty acid rules: 1. \textbf{Saturation affects shape and state}: Saturated = Straight = Solid fat. Unsaturated = Kinked = Liquid oil. 2. \textbf{Melting Point}: Longer chain = Higher MP. More saturation = Higher MP. 3. \textbf{Natural structure}: Most are even-numbered chains.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
This question asks to evaluate three fundamental statements about the chemistry of fatty acids, the building blocks of fats and oils.
Step 3: Detailed Explanation:
Let's analyze each statement:
- (A) The chain length and degree of saturation control the properties that are found within the fatty acids and lipids: This is a correct and fundamental principle. Chain length (the number of carbon atoms) and degree of saturation (the number of double bonds) are the two primary structural features that determine the physical and chemical properties of a fatty acid, such as its melting point, solubility, and susceptibility to oxidation.
- (B) Fatty acids typically contain an even number of carbon atoms: This is correct. In biological systems, fatty acids are synthesized by the sequential addition of two-carbon units (from acetyl-CoA). As a result, the vast majority of naturally occurring fatty acids have an even number of carbon atoms (e.g., palmitic acid C16, stearic acid C18, oleic acid C18). Odd-chain fatty acids exist but are much less common.
- (C) The saturated acids have higher melting points than unsaturated acids of corresponding size: This is correct. Saturated fatty acids have straight, linear chains that can pack together closely via van der Waals forces. This tight packing requires more energy (a higher temperature) to break apart, resulting in a higher melting point. Unsaturated fatty acids have "kinks" in their chains due to the double bonds, which prevent them from packing closely. This results in weaker intermolecular forces and a lower melting point.
Since all three statements are correct, the correct option must include (A), (B), and (C).
Step 4: Final Answer:
All three statements regarding the composition and properties of fats and oils are correct. Therefore, option (D) is the correct answer.