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

(N/A) Leaves require light to perform photosynthesis. When a leaf is kept in the dark,the production of chlorophyll,which is essential for photosynthesis,stops. Existing chlorophyll molecules gradually break down,causing the leaf to change from a dark green to a pale green shade.
As the chlorophyll content decreases,other pigments like xanthophylls and carotenoids,which were previously masked,become visible. This causes the leaf to turn yellow.
These pigments (xanthophylls and carotenoids) are more stable than chlorophyll because their production is not dependent on light. They are always present in the plant tissues.