Question

question 4
1 pts
if there are 12 × 10³⁵ oxygens in a sample of water, how many grams of hydrogen are in the sample?
4 grams
1 gram
8 grams
2 grams

Explanation:

Step1: Relate O to H in $\text{H}_2\text{O}$

1 mole $\text{O}$ pairs with 2 moles $\text{H}$

Step2: Calculate moles of $\text{O}$

Moles of $\text{O} = \frac{12 \times 10^{23}}{6.022 \times 10^{23}\ \text{mol}^{-1}} \approx 1.993\ \text{mol}$

Step3: Find moles of $\text{H}$

Moles of $\text{H} = 2 \times 1.993\ \text{mol} = 3.986\ \text{mol}$

Step4: Calculate mass of $\text{H}$

Mass of $\text{H} = 3.986\ \text{mol} \times 1\ \text{g/mol} \approx 4\ \text{g}$

Answer:

4 grams