Your answer is correct, I do not understand why it would be wrong.
The electron accepting tendency of an atom is known as the tendency of an atom to accept an electron. This is ranked on a scale of 0.7 to 3.98 and these species have the following values:
F: 3.98
O: 3.44
C: 2.55
Be: 1.57
Li: 0.98
Atomic mass Calcium = 40.078 a.m.u
40.078 g ---------------- 6.02x10²³ atoms
165 g -------------------- ??
165 x ( 6.02x10²³) / 40.078 => 2.47x10²⁴ atoms
hope this helps!
3.5 M has 3.5 moles per litre
so we have one litre, so we need 3.5 moles
moles = mass/molarmass
3.5 * 23 = 80.5