# Question #3ff32

May 12, 2017

$\text{Option ..........B}$

#### Explanation:

We simply need to find the molar quantity of sulfuric acid.........and multiply this molar quantity by Avogadro's number.............and then perform the subtraction.

$\text{Moles of stuff"="Mass of stuff"/"Molar mass of stuff}$

And here $\text{Moles of sulfuric acid} = \frac{98 \times {10}^{-} 3 \cdot g}{98.08 \cdot g \cdot m o {l}^{-} 1}$

And so number of sulfuric acid molecules...........

$= {N}_{A} \times \frac{98 \times {10}^{-} 3 \cdot g}{98.08 \cdot g \cdot m o {l}^{-} 1}$

$= 6.022 \times {10}^{23} \cdot m o {l}^{-} 1 \times \frac{98 \times {10}^{-} 3 \cdot g}{98.08 \cdot g \cdot m o {l}^{-} 1} = 6.0 \times {10}^{20}$ $\text{molecules}$. And if we take $3 \times {10}^{20}$ molecules away from this quantity we are left with $3 \times {10}^{20}$ such molecules.

And this represents a molar quantity of $\left(3 \times {10}^{20} \cdot \text{molecules")/(6.022xx10^23*"molecules} \cdot m o {l}^{-} 1\right) = 5 \times {10}^{-} 4 \cdot m o l$.

Not a good question, in that they are simply asking you how to use a calculator. This is non-trivial but also non-chemistry.