Question

2) what is the mass of 6.02 x 1023 atoms of arsenic?

Answer 1

Data:
Arsenic Molar Mass = 74,9216 ≈ 75 u (atomic mass unit)

Solving:

1 mole of arsenic → 75g ------------ 6,02*10²³ molecules
..................................X -------------- 1 molecule

6,02*10²³X = 75
$x = \frac{75}{6,02*10^{23}}$
$\boxed{x \approx 1,24*10^{24}grams}$