Do you think that the universe has a starting point and ending point? explain.

No

Explanation:

I don't think the universe has a starting and ending point because the universe is vast and has not been fully discovered. I think that the universe is endless because all of the stars, planets, and galaxy's have yet to be found and the end or start of the universe is also yet to be discovered so I think that the universe could go on forever.

See explanation

Explanation:

Oxygen has 6 valence electrons. To fill up the valence shell, which (when in oxygen's row) has 8 electrons, an oxygen atom wants to gain 2 electrons. Since every electron has a single negative charge, the addition of two electrons results in an oxygen ion with a charge of −2

Oxygen is in group 6 of the periodic table meaning it has 6 electrons on its outer shell so when Oxygen atom gains two electrons it results in an Oxygen Ion with a charge of -2