It is typically formed by the evaporation of salty water (such as sea water) which contains dissolved Na+ and Cl- ions. One finds rock salt deposits ringing dry lake beds, inland marginal seas, and enclosed bays and estuaries in arid regions of the world
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.
Answer:
you need only one independent variable because if not, you wont know what factors have changed your experiment.
Explanation:
I think learn to drive is the most important part