You take 80 g of Neon times 1 mol over the molar mass, 20.18 g/mol and multiply by Avogadro's number.
Shape and size doesn't affect the density of an object but temperature does affect the density of an object because the molecules act differently in different temps.
Answer:
The volume of the gas will be 78.31 L at 1.7 °C.
Explanation:
We can find the temperature of the gas by the ideal gas law equation:

Where:
n: is the number of moles
V: is the volume
T: is the temperature
R: is the gas constant = 0.082 L*atm/(K*mol)
From the initial we can find the number of moles:

Now, we can find the temperature with the final conditions:

The temperature in Celsius is:

Therefore, the volume of the gas will be 78.31 L at 1.7 °C.
I hope it helps you!