The physical properties used by scientists to describe all matter, sight, smell, taste, color, texture, mass, weight, volume, and density.
What your question for number 3
O2- stands for superoxide anion, S2- stands for sulfide anion, H- stands for hydrogen anion, and Na+ stands for sodium this all ions possess the electron configuration of noble gas because each of them (O2-, S2-, H-, and Na+) has a full outer shell.
