Question

The size of a coiled polymer chain in a dilute solution is \( R_G \) in a good solvent, \( R_I \) in an ideal solvent and \( R_P \) in a poor solvent. Select the correct ordering of sizes.

• A. \( R_G > R_I > R_P \)
• B. \( R_G < R_I < R_P \)
• C. \( R_P > R_G > R_I \)
• D. \( R_P < R_G < R_I \)

Hint:

Polymer chains expand in good solvents, remain nearly unchanged in ideal solvents, and contract in poor solvents.

Answer 1

The Correct Option is A

Step 1: Behavior of polymer chains in different solvents.
In a good solvent, polymer chains expand due to favorable interactions with the solvent, resulting in a larger coil size (\( R_G \)). In an ideal solvent, the polymer chains neither expand nor contract significantly, leading to an intermediate coil size (\( R_I \)). In a poor solvent, the polymer chains contract due to unfavorable solvent-polymer interactions, resulting in the smallest coil size (\( R_P \)).

Step 2: Conclusion.
Thus, the correct ordering of the sizes is \( R_G > R_I > R_P \), as the polymer coil is largest in a good solvent, intermediate in an ideal solvent, and smallest in a poor solvent.

Final Answer: (A) \( R_G > R_I > R_P \)