Inside surface of solar cooker is painted black because

Choose a suitable word from the box given below and fill in the blank.   

We should try to use public _____ whenever we can.

I am a quantity that can be measured or calculated. I can take many forms. I am always there when any activity takes place. I am stored by objects. I can be transferred between forms and between objects. I can never be created or destroyed.

What am I? _____

Fill in the blank with the most appropriate word:

_____ energy is used from sun by plants to make food during photosynthesis. (Light/Heat)

Choose the right word and fill in the blank:
When energy is used to do work, it gets _____ (converted, removed) from one form to another.

Choose the right word and fill in the blank:

Like the sun, even _____ (wind/moon) is a natural source of energy.