How many molecules of nitrogen monoxide (NO) are present in a 22.5 g sample?

• A. 7.82 × 10^{22} molecules
• B. 4.51 × 10^{23} molecules
• C. 1.35 × 10^{23} molecules
• D. 6.02 × 10^{24} molecules

Answer: (B)

Verified step by step guidance

1. First, determine the molar mass of nitrogen monoxide (NO). To do this, add the atomic masses of nitrogen (N) and oxygen (O). The atomic mass of nitrogen is approximately 14.01 g/mol, and oxygen is approximately 16.00 g/mol. So, the molar mass of NO is calculated as \$14.01 + 16.00$ g/mol.
2. Next, calculate the number of moles of NO in the 22.5 g sample using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\). Substitute the given mass (22.5 g) and the molar mass you found in step 1.
3. After finding the number of moles, use Avogadro's number to convert moles to molecules. Avogadro's number is \$6.022 \times 10^{23}\( molecules per mole. The formula is: \)\text{number of molecules} = \text{moles} \times 6.022 \times 10^{23}$.
4. Multiply the number of moles by Avogadro's number to get the total number of molecules in the sample.
5. Finally, express your answer in scientific notation to match the format of the options provided.