Question

Which option is true for Fischer projection formulas?

(A) They must be kept in the plane of paper.
(B) They are not allowed to flip them over.
(C) They must be rotated in the plane of paper by 90°.
(D) They must be rotated in the plane of paper by 180°.
Choose the correct answer from the options given below:

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

Hint:

In Fischer projections, you can rotate by 90° but not 180°, and the structure must remain in the plane of the paper.

Answer 1

The Correct Option is B

Step 1: Fischer projection formula rules.
- Fischer projections represent molecules in a 2D plane with vertical and horizontal bonds to show the configuration of stereoisomers.
- (A): Fischer projections must be in the plane of the paper to represent the correct 3D configuration.
- (B): The molecule can be flipped over in the Fischer projection, but it would reverse the configuration of the chiral centers, which is not allowed in certain cases.
- (C): Fischer projections can be rotated by 90° in the plane, and the configuration remains the same for simple molecules.
- (D): A 180° rotation of a Fischer projection would change the configuration, so it is not allowed.
Step 2: Conclusion. Thus, the correct option is: \[ \text{(A), (B), and (C)} \]
Final Answer: \[ \boxed{\text{(A), (B) and (C) only}} \]