At carbon atom III chlorophyll a has

Solution(By Examveda Team)

At carbon atom III chlorophyll a has a Methyl group.
Chlorophyll a is a specific form of chlorophyll used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light, and it is a poor absorber of green and near-green portions of the spectrum.
The molecular structure of chlorophyll a consists of a chlorin ring, whose four nitrogen atoms surround a central magnesium atom, and has several other attached side chains and a hydrocarbon tail formed by a phytol ester. CH₃ is the methyl group at the C-7 position chlorophyll a.