How many moles of atoms are Contained in?

You need three pieces of information to work out those answers:

1: The atomic mass of the elements, which is found on a periodic table (it's the larger of the two numbers next to the chemical symbol).

2: The number of atoms in a mole, which is known as Avogadro's number (Google it)

3: The mass of one mole of atoms of any given element in grams is the same as the atomic mass. In other words, since carbon has an atomic mass of 12, one mole of carbon atoms will have a mass of 12 g. This goes for molecules too. Water has a molecular mass of 18, so one mole of water molecules has a mass of 18 grams.

a)10.02 g Ca
n=10.02/40.08=1/4=0.25 moles
1mole----------> 6.022 x10²³ atoms
1/4 moles ---------------------> 6.022/4 x10²³ atoms
=1.555 x10²³ atoms

Others)

92.91g of P?
M.M.=31*4=124
n=92.91/124=0.749274194=0.75=3/4

1mole----------> 6.022 x10²³ atoms
3/4 moles ---------------------> 3*6.022/4 x10²³ atoms
=3*1.555 x10²³ atoms...................answe r(a)
=4.665 x10²³ atoms...................