Which of the following nitrogenous base is NOT present in RNA?

The correct answer is Option (4) → Thymine

Option (1) Adenine — Present in RNA. A purine found in both DNA and RNA.

Option (2) Guanine — Present in RNA. Also a purine of both.

Option (3) Cytosine — Present in RNA. A pyrimidine of both.

Option (4) Thymine — Not present in RNA. Thymine is found only in DNA; RNA has uracil in its place.

NCERT Extract:
Structure of Polynucleotide Chain – “… There are two types of nitrogenous bases – Purines (Adenine and Guanine), and Pyrimidines (Cytosine, Uracil and Thymine). Cytosine is common for both DNA and RNA and Thymine is present in DNA. Uracil is present in RNA at the place of Thymine.”