Question

What is approximate size of a molecule

Answer 1

Some of the largest molecules are macromolecules or supermolecules. The smallest molecule is the diatomic hydrogen (H2), with a bond length of 0.74 Å=0.74×10^-10 Effective molecular radius is the size a molecule displays in solution. The table of permselectivity for different substances contains examples.

in case of wate
The approximate distance between the atoms, which takes up most space, is 250 picometers. The sizes of the atoms add up to around 25 picometers. Thus, the size of a molecule of water is approximately 275 picometers.