Chlorophyll is a naturally occurring chelate compound in which central metal is

Answer: (a) Magnesium

Chlorophyll is a porphyrin ring holding a magnesium ion at its centre.

The idea

A chelate is a compound in which a ring-shaped organic molecule grips a metal ion at its centre, like a claw. Chlorophyll and haemoglobin are built on almost the same ring. The plant’s ring holds magnesium; the blood’s ring holds iron.

Ring + magnesium → chlorophyll → green → traps light → Ring + iron → haem → red → carries oxygen

Why the others are wrong

(b) Copper is the metal of haemocyanin, the blue blood of octopuses and crabs.

(d) Iron sits in the same kind of ring in haemoglobin (heme) — the classic mix-up.

The trap

Haemoglobin and chlorophyll have almost the same ring structure. Heme holds iron, chlorophyll holds magnesium.

Also know

When soil lacks magnesium, a plant cannot make enough chlorophyll and its older leaves turn yellow between the veins. This yellowing is called chlorosis.