Which of these compounds has the same empirical and molecular formulae?
C2H4
C3H8
C4H10
C5H10
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Which of these compounds has the same empirical and molecular formulae?
C2H4
C3H8
C4H10
C5H10
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Which of these atoms has the most neutrons?
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What is the relative formula mass of hydrated sodium carbonate, Na2CO3.10H2O?
[Ar values: H = 1.0 C = 12.0 O = 16.0 Na = 23.0]
106
142
263
286
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There are 6.02 × 1023 atoms in 0.25 mol of
He
H2O
BH3
CH4
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Ammonium iron(II) sulfate, (NH4)2Fe(SO4)2·6H2O, is a double salt that is used as a source of iron(II) ions.
What is the relative formula mass of the double salt?
[Ar values: H = 1.0 N = 14.0 O = 16.0 S = 32.1 Fe = 55.8]
277.9
284.0
392.0
447.8
Ammonium sulfate is used in the preparation of the double salt.
What types of bond are present in ammonium sulfate?
ionic only
covalent and ionic only
dative covalent and ionic only
ionic, covalent and dative covalent
1.80 × 1023
2.41 × 1023
3.01 × 1023
6.62 × 1023
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The equation for the complete combustion of hexane is shown.
C6H14 + 9 1⁄2O2 → 6CO2 + 7H2O
How many molecules of carbon dioxide are formed when 2 × 10−3 mol of hexane undergoes complete combustion?
[Avogadro constant L = 6.02 × 1023 mol−1]
1.20 × 1021
7.22 × 1021
8.43 × 1021
3.18 × 1023
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Barium hydroxide reacts with sulfuric acid as shown.
Ba(OH)2 (aq) + H2SO4 (aq) → BaSO4 (s) + 2H2O (l)
Which is the ionic equation for this reaction?
Ba2+ (aq) + 2OH− (aq) + 2H+ (aq) + S (aq) → BaSO4 (s) + 2H2O (l)
Ba2+ (aq) + S (aq) → BaSO4 (s)
OH− (aq) + H+ (aq) → H2O (l)
Ba2+ (aq) + 2OH− (aq) + 2H+ (aq) + S (aq) → Ba2+ (s) + S (s) + 2H2O (l)
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An oxide of lead contains 90.7% by mass of lead.
What is the formula of this oxide?
[Ar values: O = 16.0 Pb = 207.2]
PbO
PbO2
Pb2O3
Pb3O4
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A sample of seawater with a mass of 1 kg contains 6 × 10−9 g of gold.
How many atoms of gold, to one significant figure, are there in 1 g of this seawater?
[Ar value: Au = 197 Avogadro constant = 6 × 1023 mol−1]
2 × 1010
4 × 1012
2 × 1013
4 × 1015
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