Which is the central metal ion in chlorophyll?

Which fractions of the visible spectrum of solar radiations are primarily absorbed by carotenoids of the higher plants?

Which of the following act as accessory pigments?

Suppose there were plants that had a high concentration of Chlorophyll-$b$,but lacked Chlorophyll-$a$. Would they carry out photosynthesis? Then why do plants have Chlorophyll-$b$ and other accessory pigments?

Which of the following wavelengths of light is absorbed maximum for photosynthesis?

If chlorophyll is burnt,which element will be left as the residue?