Ah, the classic case of the elusive helium! Let's solve this puzzle. So, we know the total number of moles of nitrogen and oxygen. But first, let me just remind you that helium is a noble gas - it likes to stay hidden and doesn't react much with other elements. It's like the introverted cousin of the periodic table!
Now, since we know the total pressure, we can apply the ideal gas law, which states that PV = nRT. Here, P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. We can use this to find the total number of moles in the mixture.
The number of moles of helium can be obtained by subtracting the moles of nitrogen and oxygen from the total moles. Then, we can use the molar mass of helium (4.00 g/mol) to find the mass of helium in grams.
Let's do the math together, shall we?