Question

The reason for double helical structure of DNA is operation of

• A. Van der Waal's forces
• B. Dipole-dipole interaction
• C. Hydrogen bonding
• D. Electrostatic attractions

Answer 1

The correct option is C Hydrogen bonding

The reason for double helical structure of DNA is operation of Hydrogen bonding between complementary bases. Cytosine forms three hydrogen bonds with guanine, and adenine forms two hydrogen bonds with thymine. $\text{Adenine}=\text{Thymine},\text{Guanine}\equiv \text{Cytosine}$
Hence correct option is (c).