The double helical structure of $DNA$ was proposed by

Which among the following is a double ring containing nitrogen base present in nucleic acids?

$DNA$ consists of two polynucleotide chains. Each chain forms a right-handed spiral with how many bases in one turn of the spiral?

The pyrimidine bases present in $DNA$ are

Which of the following statements is not true about $RNA$?

The number of hydrogen bonds between guanine and cytosine; and between adenine and thymine in $DNA$ is