Calcium has an atomic mass of 40 and an atomic number of 20, so the number of neutrons must be

The atom would have 20 neutrons.

Mass number = neutrons + protons

40 = neutrons + 20

neutrons = 40 – 20 = 20

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