List of top Chemistry Questions on Atomic and Molecular Masses

Determine the empirical formula of an oxide of iron, which has 69.9% iron and 30.1% dioxygen by mass.
Calculate the atomic mass (average) of chlorine using the following data: 
                                                   % Natural Abundance                                Molar Mass 
\(^{35}\text{Cl}\)                                                         75.77                                                34.9689 
\(^{37}\text{Cl}\)                                                         24.23                                                36.9659
How many significant figures should be present in the answer of the following calculations?
  1. \(\frac {0.02856 × 298.15 × 0.112}{0.5785}\)
  2. \(5 × 5.364\)
  3. \(0.0125 + 0.7864 + 0.0215\)
In three moles of ethane \((\text{C}_2\text{H}_6)\), calculate the following: 
(i) Number of moles of carbon atoms. 
(ii) Number of moles of hydrogen atoms. 
(iii) Number of molecules of ethane.
If the speed of light is 3.0×108 ms–1, calculate the distance covered by light in 2.00 ns.
Which one of the following will have the largest number of atoms?