What is the rule for the pairing of nitrogen-containing bases in the DNA molecule? And in the RNA?
The rule for the pairing of nitrogen-containing bases of the polynucleotide chains that form the DNA molecule is pyrimidine base binds to purine base, under the condition that thymine (T) binds to adenine (A) and cytosine (C) binds to guanine (G).
In RNA there is no binding between nitrogen-containing bases. That is because RNA is formed of only one polynucleotide chain; differently, DNA is formed of two chains. It is therefore not correct to question base pairing in RNA.