Correct option is C
Explanation-
Option a - Chlorophyll-a has a -CH₃ group in its porphyrin-like ring structure.
This is correct. Chlorophyll-a contains a methyl (-CH₃) group at the C-7 position of the porphyrin ring.
Option b - Chlorophyll-b has -CHO group in its porphyrin-like ring structure.
This is correct. Chlorophyll-b contains a formyl (-CHO) group at the C-7 position instead of the methyl group in chlorophyll-a.
Option c - Only chlorophyll-a, but not chlorophyll-b, has a Mg²⁺ coordinated at the centre of the porphyrin-like ring structure.
This is NOT correct. Both chlorophyll-a and chlorophyll-b have a central Mg²⁺ ion coordinated in the porphyrin ring.
Option d - The long hydrocarbon tails of chlorophyll anchor them in the photosynthetic membrane.
This is correct. Chlorophyll molecules have a phytol tail (a long hydrocarbon chain) that helps anchor them in the thylakoid membranes.
So, the correct answer is option c - Only chlorophyll-a, but not chlorophyll-b, has a Mg²⁺ coordinated at the centre of the porphyrin-like ring structure.
