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
Which of the following masses of calcium hydroxide, Ca(OH)2, contains 20 moles? (Ar of H = 1, Ar of O = 16, Ar of Ca = 40)
1.16 kg
1.48 kg
2.28 kg
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%
What is the empirical formula of octane C8H18?
CH2
C4H9
C8H18
Which of the following statements about hydrated salts is false?
The degree of hydration can be determined by heating it to constant mass and taking measurements before and after heating.
When heated, the water of crystallisation evaporates to leave the anhydrous salt.
The mass of the anhydrous salt will be greater than the mass of the hydrated salt.