Answer:
1.51e23 atoms
Explanation:
First, using the molar mass of Si (28.1 g/mol), determine the # of moles of Si we have. Then use Avogadro's number (6.022e23 atoms = 1 mol) to convert the # of moles to the # of Si atoms.
(7.02 g Si)([tex]\frac{1 mol}{28.1 g}[/tex]) = 0.250 mol Si
(0.250 mol Si)([tex]\frac{6.022*10^{23} atoms }{1 mol}[/tex]) = 1.51e23 atoms
