I've always been told that it's eight. This is only because the atom has to have the saem protons (positively charged) neutrons and electrons (negatively charged). However this does not occur with all atoms. :)
Number of moles =

so to calculate molar mass (Molecular weight of compound):
Molecular weight =

=

= 50 g / mole
Now we calculate molecular weight of each compound in choices:
a) C₂H₄O = 44
b) CO₂ = 44
c) CH₃Cl = 50.4 ALMOST 50 so this is the correct answer
d) C₂H₆ = 30
Answer:
3.59x10⁻⁴ mol
Explanation:
Assuming ideal behaviour we can solve this problem by using the<em> PV=nRT formula</em>, where:
- R = 8314.46 Pa·L·mol⁻¹·K⁻¹
We<u> input the data given by the problem</u>:
- 205 Pa * 5.68 L = n * 8314.46 Pa·L·mol⁻¹·K⁻¹ * 390.4 K
And <u>solve for n</u>: