what is the mass in grams?

Question

a) 3.011 x 10^23 atoms F
b)1.50 x 10^23 atoms Mg
c)4.50 x 10^12 atoms Cl
d)8.42 x 10^18 atoms Br
e) 25 atoms w
f) 1 atom Au
can you please explain a and b to me then i'll come back later and see if i did the rest right? Thanks in advance
it needs to be in scientific notation i think.

Answer 1

answered above.