Answer:
Volume = 16.8 Liters
Step-by-step explanation:
First, we will need to get the number of moles in the sample as follows:
number of moles = mass / molar mass
number of moles of CH4 = 4 / (12+4) = 4 / 16 = 0.25 moles
number of moles of He = 2 / 4 = 0.5 moles
Total number of moles in the sample = 0.25 + 0.5 = 0.75 moles
Now, at STP, one mole of any gas occupies a volume of 22.4 Liters. To know the volume occupied by 0.75 moles at STP, all we have to do is cross multiplication as follows:
1 mole .............> 22.4 liters
0.75 moles .......> ?? liters
Volume = (0.75*22.4) / 1
Volume = 16.8 liters
Hope this helps :)