Question

Match the following with their pKa values 

• A. I - a, II - d, III - c, IV – b
• B. I-a, II - b, III - c, IV – d
• C. I-b, II - a, III - d, IV – c
• D. I-c, II -d, III - a, IV – b

Hint:

pKa values are a useful measure of the strength of acids: lower pKa values correspond to stronger acids. Phenol has a high pKa value, while picric acid has a lower one.

Answer 1

The Correct Option is D

The pKa values of acids indicate their acidity. The lower the pKa value, the stronger the acid. Below is the pKa value matching with each compound: - Phenol (I) has a pKa of 16, which is relatively high and indicates weak acidity. Thus, it matches with (c).
- p-Nitrophenol (II) has a pKa of 0.78, which is relatively low, indicating it is a stronger acid compared to phenol. Thus, it matches with (d). - Ethyl alcohol (III) has a pKa of 10, indicating it is weaker than phenol. Therefore, it matches with (a).
- Picric acid (IV) has a pKa of 7.1, which is low, making it a relatively strong acid. Thus, it matches with (b).
Thus, the correct answer is option (4).