(b) : Chlorophyll is the green pigment present in plants and some photosynthetic bacteria. The empirical formula of chlorophyll-a molecule is C55H72O5N4‌Mg. It consist of a porphyrin head and a phytol tail. Porphyrin is a cyclic tetrapyrrole structure, having a magnesium atom in the centre. Tail consists of phytol alcohol and it is attached with one of the pyrrole rings.