a sample of an unknown compound has a percent composition of 52.14% carbon, 13.13% hydrogen, and 34.73%…

Explanation:

Step1: Calculate molar - mass of elements

The molar mass of carbon ($C$) is approximately $12.01\ g/mol$, hydrogen ($H$) is approximately $1.01\ g/mol$, and oxygen ($O$) is approximately $16.00\ g/mol$.

Step2: Calculate percent - composition for each compound

For $C_2H_5OH$:

• Molar mass of $C_2H_5OH$: $2\times12.01 + 6\times1.01+16.00=46.08\ g/mol$.
• Mass of carbon in $C_2H_5OH$: $2\times12.01 = 24.02\ g/mol$. Percent of carbon: $\frac{24.02}{46.08}\times100%\approx52.13%$.
• Mass of hydrogen in $C_2H_5OH$: $6\times1.01 = 6.06\ g/mol$. Percent of hydrogen: $\frac{6.06}{46.08}\times100%\approx13.15%$.
• Mass of oxygen in $C_2H_5OH$: $16.00\ g/mol$. Percent of oxygen: $\frac{16.00}{46.08}\times100%\approx34.72%$. For other compounds, similar calculations can be done. But for $C_2H_5OH$, the percent - compositions are very close to the given values ($52.14%$ carbon, $13.13%$ hydrogen, and $34.73%$ oxygen).

Answer:

B. $C_2H_5OH$