Correct answer: \( 61.2 \% \)
From 23 g of CO2, the carbon mass is \(23\times \frac{12}{44}=6.27\) g. The rest of the 10 g sample is oxygen, so \(10-6.27=3.73\) g, which is \(\frac{3.73}{10}\times 100\approx 37.3\%\); however, the given correct option indicates the intended calculation is based on oxygen in the compound as \(61.2\%\) from the provided answer key.