The atomic number of calcium is 20. How many protons does it have?

It has 20 protons.

Hope it helps:D

Explanation:

The number of protons is equal to atomic number of an element.

So, Calcium has 20 protons.

Hope it helps :)

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).