A balloon containing helium gas expands from 230 mL to 860 mL as more helium is added. What was the initial quantity of helium present if the expanded balloon contains 3.8 × 10-4 mol, assuming constant temperature and pressure? Which of the variables are known?

Answer and Explanation:

For computing the initial quantity of helium we have to apply the law of ideal gas which is shown below:

Now we have to compute the ratio between the initial and the final numbers of moles which is

The statement defines that

Therefore

And, the variables are known is starting volume and ending gas quantity