Answer is: mass of silver chloride is 0.573 grams.
Balanced chemical reaction:
2AgNO₃ + [Co(NH₃)₅Cl]Cl₂ → 2AgCl + [Co(NH₃)₅Cl](NO₃)₂.
m(Co(NH₃)₅Cl]Cl₂) = 500 mg ÷ 1000 mg/g = 0.5 g.
n(Co(NH₃)₅Cl]Cl₂) = 0.5 g ÷ 250.4 g/mol.
n(Co(NH₃)₅Cl]Cl₂) = 0.002 mol.
From chemical reaction: n(Co(NH₃)₅Cl]Cl₂) : n(AgCl) = 1 : 2.
n(AgCl) = 2 · 0.002 mol = 0.004 mol.
m(AgCl) = 0.004 mol · 143.32 g/mol.
m(AgCl) = 0.573 g.