Safety glasses should be worn any time you are doing an experiment, especially one that involves chemicals or chemical reactions. They prevent chemicals or other materials from getting on or in your eye, and can prevent anything from mild discomfort to permanent blindness.
Some pairs of safety glasses have magnifying glasses on them, similar to bifocals. They can be used to more carefully examine something in an experiment.
You can tell the difference by How shiny it is and by how heavy it is
Answer:
Nitrogen
Explanation:
Nitrogen present 78% in the earth's atmosphere

The nucleus of an atom of the element is positively charged and atom has a hollow space inside it.
Explanation:
This experiment was conducted by Rutherford in this experiment. He placed a gold foil and surround it with a screen.
And He exposed gold foil in alpha particles rays in which he noticed that most rays passed through atom which conclude that atom has a large space, some rays get deflected and some reverse their path this show that the positive charge of nucleus of an atom.