Answer:
300 g
Step-by-step explanation:
To solve this convert atoms to moles to grams. To convert atoms to moles, you will need Avogadro's number (6.022*10²³ atoms/mol), and to convert moles to grams, you will need the atomic mass of Cl (34.45 g/mol).
Divide the given mass of Cl by Avogadro's number to find moles. Get 8.718..
Multiply the moles by the atomic mass. Get 300.3..
Your answer is 300 g because of significant figures.