Why is the colour of a leaf kept in the dark frequently yellow, or pale green? Which pigments do you think is more stable?

If in case of a motion, displacement is directly proportional to the square of time elapsed, what do you think about its acceleration i.e., constant or variable? Explain why?

What do you understand by electron affinity of an element ? Why electron affinity of chlorine is more than that of fluorine.

Look at leaves of the same plant on the shady side and compare it with the leaves on the sunny side. Or, compare the potted plants kept in the sunlight with those in the shade. Which of them has leaves that are darker green? Why?

An element is involved in the formation of mitotic spindle. Which part of the plant do you expect it to be present? Why? Name the element. Where else can it be present?

Why do you think the noble gases are placed in a separate group?

RuBisCo is an enzyme that acts both as a carboxylase and oxygenase. why do you think RuBisCo carries out more carboxylation in C_4 plants?

Why do members of Phaeophyceae vary in colour from olive green to various shades of brown?

A blackish brown coloured solid 'A' when fused with alkali metal hydroxides in presence of air, produces a dark green coloured compound 'B' which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound 'C' Identify A, B and C and write the reactions involved.