Question

A double stranded DNA contains 42 percent of G and C. The percentage of ‘T’ is:

• A. 58
• B. 23
• C. 29
• D. 21

Hint:

Chargaff’s rule ensures that A = T and G = C in double-stranded DNA.

Answer 1

The Correct Option is C

Step 1: Understanding Chargaff’s Rule 
According to Chargaff's rule, the amount of adenine (A) equals thymine (T), and the amount of cytosine (C) equals guanine (G). 
Step 2: Given Data 
- The sum of G and C is 42%. 
- Therefore, A and T must make up the remaining 58%, and since A = T, each must be 29%. 
Step 3: Conclusion 
Thus, the percentage of thymine (T) is 29%.