The relative atomic mass of an element is the mass compared to which element?
nitrogen-14
oxygen-16
carbon-12
Which is the correct relative molecular mass, Mr, for ethane C2H6? (Ar of C = 12, Ar of H = 1)
30
144
36
What is the percentage by mass of carbon in calcium carbonate CaCO3? (Ar of Ca = 40, Ar of C = 12, Ar of O = 16)
12
40
48
How many moles are present in 1 g of NaOH? (Ar of Na = 23, Ar of O = 16, Ar of H = 1)
0.05
0.25
0.025
In the following equation, what is the molar ratio between hydrochloric acid and copper(II) oxide? 2HCl + CuO → CuCl2 + H2O
1 : 2
2 : 1
1 : 1
In the reaction shown by the following equation, what mass of sulfur dioxide can be produced when 4 g of sulfur reacts with excess oxygen? (Ar of S = 32, Mr of O2 = 32, Mr of SO2 = 64). S + O2 → SO2
8 g
16 g
64 g
In an experiment, the actual yield is 8.4g but the theoretical yield is 17.0g. what is the percentage yield?
24.7%
49.4%
50.6%