The dictionary definiton of light is:
the natural agent that stimulates sight and makes things visible.
I'll paraphrase/give a scientific definition:
Light is made of subatomic particles called photons, which jumps electron shells when they're excited, effecting the electromagnetic spectrum, creating visible light.
Hope this helps. Might not as I'm not perfect on this topic yet.
Atomic number The atomic number of each element is different than other Elements.
Sorry, but where are the ‘items’?
Student B because it requires a hypothesis
Watt stands for power that is energy per unit time