Answer
See answer below.
Work Step by Step
a) Molecular formula: $C_7H_5NO_3S$
Structural formula:
$\begin{smallmatrix}
& & & & & & O & & & & \\
& & & & & & || & & & & \\
& & C & & & & C & & & & \\
& /& & \backslash\backslash& & /& &\backslash & & & \\
C & & & & C& & & & N& -&H \\
|| & & & & | & & & /& & & \\
C & & & & C & - & S & =& O& & \\
&\backslash & & /& & &|| & & & & \\
& & C& & & & O & & & & \\
\end{smallmatrix}$
b) Saccharin's molecular weight: $183.18\ g/mol$
In 125 mg:
$125\ mg\times10^{-3}\ g/mg\div183.18\ g/mol=6.82\times10^{-4}\ mol$
c) Atomic weight of sulfur: $32.06\ g/mol$
Mass percent in saccharin: $32.06\div183.18\times 100\%=17.5\%$
In 125 mg:
$125\times 17.5\div100=21.88\ mg$
