A. Jumlah mol gas H2S
\begin{equation*}
\begin{split}
\text{P} \:.\: \text{V} & = \text{n} \:.\: \text{R} \:.\: \text{T} \\\\
2 \:.\: 5& = \text{n}\:.\: 0,082 \:.\: (27 + 273) \\\\
10 & = \text{n} \:.\: 0,082 \:.\: 300 \\\\
\text{n} & = \frac{10}{0,082 \:.\: 300} \\\\
\text{n} & = 0,41 \text{ mol } \ce{H2S}
\end{split}
\end{equation*}
B. Massa senyawa H2S
\begin{equation*}
\begin{split}
\text{n} & = \frac{\text{m}}{\text{Mr}} \\\\
0,41& = \frac{\text{m}}{ (2 \times 1) + 32} \\\\
\text{m} & = 0,41 \times 34 \\\\
\text{m} & = 13,94 \text{ gram } \ce{H2S}
\end{split}
\end{equation*}
C. Jumlah partikel H2S dalam tabung tersebut
\begin{equation*}
\begin{split}
\text{n} & = \frac{\text{N}}{\text{N}_{\text{A}}} \\\\
0,41& = \frac{\text{N}}{6,02 \times 10^{23}} \\\\
\text{N} & = 0,41 \times 6,02 \times 10^{23} \\\\
\text{N} & = 2,468 \times 10^{23} \: \text{molekul } \ce{H2S}
\end{split}
\end{equation*}