Answer
There are 10.1 g of $Ne$ in 11.2 L of $Ne$ gas at STP.
Work Step by Step
1. Setup the conversion factors:
For a gas at STP conditions, we can use the equality: $1 \space mole = 22.4 \space L$:
$\frac{1 \space mole \space (Ne)}{22.4 \space L \space (Ne)}$ and $\frac{22.4 \space L \space (Ne)}{1 \space mole \space (Ne)}$
Molar mass of $Ne$: 20.18 g/mole
$ \frac{1 \space mole \space (Ne)}{ 20.18 \space g \space (Ne)}$ and $ \frac{20.18 \space g \space (Ne)}{1 \space mole \space (Ne)}$
2. Calculate the mass of $Ne$ in that sample:
$11.2 \space L \space (Ne) \times \frac{1 \space mole \space (Ne)}{22.4 \space L \space (Ne)} \times \frac{20.18 \space g \space (Ne)}{1 \space mole \space (Ne)} = 10.1 \space g \space (Ne)$