How many moles are 4.20 * 10 ^ 25 atoms of Ca?

~69.744 moles of Ca

Explanation:

Using Avogadro's constant , we know that:

1 mole = 6.022 x 10^23 atoms

S0, the number of moles in 4.20 x 10^25 atoms of Ca:

=(4.20 x 10^25 x 1 )/(6.022 x 10^23)

~69.744 moles of Ca

Q2:How many atoms are in 0.35 moles of oxygen?

1 mole = 6.022 x 10^23 atoms

S0, the number of atoms in 0.35 moles of  oxygen:

=[0.35 x (6.022 x 10^23)]

=2.1077 x 10^23 atoms of Oxygen

Hope it helps:)

precipitation

explanation:

when it goes from cloud to rain/back to earth in the form of rain