11 markeasy
Which of these compounds has the same empirical and molecular formulae?
Choose your answer
C2H4
C3H8
C4H10
C5H10
Chemistry
10 questions · 12 marks · ≈ 12 min
Which of these compounds has the same empirical and molecular formulae?
Choose your answer
C2H4
C3H8
C4H10
C5H10
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]
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106
142
263
286
There are 6.02 × 1023 atoms in 0.25 mol of
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He
H2O
BH3
CH4
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]
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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?
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ionic only
covalent and ionic only
dative covalent and ionic only
ionic, covalent and dative covalent
What is the total number of ions present in 0.1 mol of the double salt? [Avogadro constant (L) = 6.02 × 1023mol−1]
Choose your answer
1.80 × 1023
2.41 × 1023
3.01 × 1023
6.62 × 1023
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]
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1.20 × 1021
7.22 × 1021
8.43 × 1021
3.18 × 1023
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?
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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)
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]
Choose your answer
PbO
PbO2
Pb2O3
Pb3O4
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]
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2 × 1010
4 × 1012
2 × 1013
4 × 1015
How many molecules are there in 8.8 g of carbon dioxide, CO2?
[Avogadro constant, L = 6.02 × 1023 mol-1; Mr(CO2) = 44.0]
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1.20 × 1023
3.61 × 1023
6.02 × 1023
5.30 × 1024