11 mark
Leucine is an essential amino acid used in the synthesis of proteins in the body.
What is the relative molecular mass of leucine?
144
86
125
131
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Relative Masses of Atoms & Molecules (Cambridge (CIE) O Level Chemistry): Exam Questions
Exam code: 5070
2 hours30 questions
21 mark
What mass of magnesium oxide is formed when 21 g of magnesium carbonate thermally decomposes via the following equation. (Ar = Mg = 24, C = 12, O = 16)
MgCO3 (s) → MgO (s) + CO2 (g)
10
11
20
22
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31 mark
Which statement describes the relative atomic mass of an element?
the mass of one atom of the element compared to 1/12th of the mass of an atom of 12C
the average mass of the isotopes of the element compared to 1/12th of the mass of an atom of 12C
the average mass of the isotopes of the element compared to the mass of an atom of 12C
the sum of the relative atomic masses of the atoms shown in a formula
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41 mark
Sulfur forms simple molecules.
One molecule of sulfur has a relative molecular mass of 256.
What is the formula of a sulfur molecule?
S2
S4
S8
S16
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51 mark
Which substance has a relative formula mass rather than a relative molecular mass?
hydrogen chloride, HCl
carbon dioxide, CO2
magnesium oxide, MgO
chlorine, Cl2
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11 mark
6 g of hydrogen react with 48 g of oxygen to form water. A chemist performs the same reaction using 2 g of hydrogen.
What mass of oxygen is required to combine with the hydrogen?
24 g
12 g
16 g
72 g
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21 mark
Magnesium nitrate is an ionic compound.
What is its relative formula mass?
86
100
124
148
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31 mark
A compound of an element E with hydrogen has the formula EH4.
The compound contains 87.5% by mass of E.
What is the relative atomic mass of E?
(Ar: H = 1)
4
28
32
112
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41 mark
Hydrated magnesium sulfate has the formula MgSO4·7H2O.
What is its relative formula mass?
(Ar: H = 1, O = 16, Mg = 24, S = 32)
120
138
232
246
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51 mark
What is the relative formula mass of ammonium sulfate, (NH4)2SO4?
(Ar: H = 1, N = 14, O = 16, S = 32)
84
114
128
132
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11 mark
Ammonia is manufactured by the reaction of hydrogen and nitrogen in the Haber process, as shown in the equation below:
N2 + 3 H2 → 2 NH3
16.8 tonnes of ammonia can be produced from 14 tonnes of nitrogen.
How much nitrogen is needed to produce 51 tonnes of ammonia?
42.5
34
17
24.5
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21 mark
A sample of a metal, X, contains two isotopes, 69X and 71X.
In this sample, 60% of the atoms are 69X and 40% of the atoms are 71X.
The metal forms the sulfate X2(SO4)3.
What is the relative formula mass of this sulfate? (Ar: O = 16, S = 32)
235.6
357.8
427.6
428.0
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31 mark
Which of these ionic compounds has the greatest relative formula mass?
(Ar: N = 14, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5, Ca = 40)
calcium chloride
calcium nitrate
sodium sulfate
magnesium sulfate
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41 mark
Statements about relative masses are given.
1 The relative formula mass of magnesium chloride, MgCl2, is 95.
2 The relative molecular mass of chlorine gas is 35.5.
3 The relative atomic mass of chlorine is not a whole number because chlorine exists as a mixture of isotopes.
Which statements are correct?
(Ar: Mg = 24, Cl = 35.5)
1, 2 and 3
1 and 2 only
1 and 3 only
2 and 3 only
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51 mark
Calcium chloride has the formula CaCl2.
Which statement about calcium chloride is correct?
Its relative atomic mass is 111.
Its relative molecular mass is 111.
Its relative formula mass is 111.
Its relative formula mass is 75.5.
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