What is chlorophyll and why does it impart only green colour?

 Chinu, a sweet boy of nine, was playing with his friends Suraj and Fenny in the garden. But, after a while, they got tired and decided to sit on the soft grass. Chinu's eyes were wandering around the park, and he saw multiple colours, yellow, blue, magenta, and many more. But the one that he saw almost everywhere was the colour green. He noticed that almost every plant and tree had green leaves. So he thought maybe leaves like green a lot, and it might be their favourite colour and hence chose that colour. He used to wear a white shirt a lot, white being his favourite colour. 

But then how can every plant's favourite colour be green? So there must be something behind this green of leaves!

After playing, he ran home and called Shweta, his elder sister, to ask about something he observed in the park. Shweta was amazed by the boy's curiosity to know things. 

Shweta replied, "There is a chemical called Pigment which gives things their colour. The Pigment is why your hairs are black, and our dog is beige and the flowers this colourful. Now, plant leaves also have a special pigment called chlorophyll that gives them their green colour. The word chlorophyll has roots in the Greek language. Where 'khloros' mean green and  'phullos' mean leaves."

Chinu asked, "But why only green? Why doesn't this chlorophyll give leaves a pink or orange colour?"

Shweta smiled and said, "Do you know all the colours mix to make white light. This is the light that we get from the sun. It has all the colours you can imagine. Now pigments can absorb some colours of the white light, but it reflects the ones they can't absorb, and we see them as the object containing that Pigment's colour. Now, can you guess Chinu why chlorophyll gives plant its green colour?"

Chinu enthusiastically replied, "Yes didi, is it because that chlorophyll absorbs all colours of the white light but not green and reflects it? So, we see green colour in the leaves."

Shweta smiled and nodded. 

Chinu asked, "Then why do some leaves have leaves of other colours like purple or white or other colours? Is it because they reflect some other colours too."

Shweta said, "Such leaves have some other pigments of that colour in large quantities, and that's why we see certain other colours prominently. But that doesn't mean that they don't have chlorophyll. They still do. But it is deep within the leaves."

Chinu got intrigued by this and asked further, "Then what does this chlorophyll do after absorbing so many colours of white light?"

Shweta replied, "The chlorophyll is essential for life. It absorbs this much of light from the sun, which it further uses as the energy source to power a process called photosynthesis, by which plants make their food. Without chlorophyll plants can't make food."

Chinu asked why he couldn't have the chlorophyll so that he could make his food too and never have to eat.

Shweta laughed and said, "Just like we make food in the kitchen, plants make food in their kitchen called plastid. We don't have those types of cellular kitchens in our bodies. Moreover, photosynthesis is not efficient in supplying our very high energy needs. We need 24oo kcal of energy every day, and for that, if we had photosynthesis, we might need to sit in the sun for 150 hours a day."

Chinu gasped and said, "Is that so? No, I don't want chlorophyll when I can enjoy delicious food that mum makes." 

And then they both go inside as their mother calls them for dinner.