How to calculate volume of a gas at STP?

[Mackydoodle]

Homework Statement

Calculate the volume of .250 g of helium at STP.
This seems so simple but I keep getting the wrong answers.
If someone could walk me through how to do this problem so I will know how to do them for our test. Our book doesn't give a good example.

Homework Equations

I know gasses occupy 22.4 L at STP but other then that... I'm not sure how to set up this equation

The Attempt at a Solution

 

[epenguin]

Homework Statement

Calculate the volume of .250 g of helium at STP.
This seems so simple but I keep getting the wrong answers.
If someone could walk me through how to do this problem so I will know how to do them for our test. Our book doesn't give a good example.

Homework Equations

I know gasses occupy 22.4 L at STP but other then that... I'm not sure how to set up this equation

The Attempt at a Solution

More exactly a mole of gas occupies 22.4 L .
So how many moles is 0.25g of He? You can take the atomic mass to be 4.
Moles and atomic mass have got to be in your book so I won't come back on this.