This question has multiple parts. Work all the parts to get the most points.

Gold has compounds containing gold$($I$)$ ion or gold$($III$)$ ion. A compound of gold and chlorine was treated with a solution of silver nitrate, $AgN{O}_3,$ to convert the chloride ion in the compound to a precipitate of AgCl. A $1\mathrm{.}872mg$ sample of the gold compound gave $1\mathrm{.}154$mgAgCl. Calculate the percentage of the chlorine in the gold compound.

Percentage $=\%$

Correct

The mass of chloride ion in the AgCl from the gold chloride compound is:

$1\mathrm{.}154$mgAgCl$\frac{35\mathrm{.}45mgC{l}^{-}}{143\mathrm{.}32\text{m}\text{g}\text{A}\text{g}\text{C}\text{l}}=0\mathrm{.}2854mgC{l}^{-}$

The percentage of chloride in the $1\mathrm{.}872mg$ sample is:

$\frac{0\mathrm{.}2854mgC{l}^{-}}{1\mathrm{.}872\text{m}\text{g}\text{s}\text{a}\text{m}\text{p}\text{l}\text{e}}100\%=15\mathrm{.}25\%C{l}^{-}$

Decide whether the formula of the compound is AuCl or $AuC{l}_3.$

AuCl

$AuC{l}_3($ please answer part b only $***)$