Essential Chemistry for IGCSE - Chemical Calculations (Section 7)
1
Which of the following is used to calculate solution concentration?
Answer
(D)
Moles / Volume (dm³)
2
In a chemical reaction, what determines the maximum amount of product that can be formed?
Answer
(B)
The limiting reactant
3
What does the empirical formula of a compound indicate?
Answer
(C)
The simplest ratio of atoms.
4
What is the purpose of the 'Worked example' within the context of the provided text?
Answer
(B)
To provide a step-by-step illustration of how to solve a problem.
5
What is the molar mass of carbon dioxide (CO2)? (C = 12, O = 16)
Answer
(C)
44 g/mol
6
What are the main steps to finding the empirical formula?
Answer
(A)
Find the mass of each element, divide by their relative atomic mass, and find the simplest ratio.
7
Which of the following is (are) used in an acid-alkali titration?
Answer
A
B
C
D
8
What is the volume occupied by 2 moles of any gas at room temperature and pressure (RTP)?
Answer
(D)
48 dm³
9
What does 'empirical formula' represent about a compound?
Answer
(B)
The simplest whole-number ratio of atoms.
10
Which of the following is a correct formula for calculating percentage yield?
Answer
(A)
((Actual yield / Theoretical yield) * 100)
11
What is the molar mass of glucose (C6H12O6)? (C=12, H=1, O=16)
Answer
(A)
180 g/mol
12
How many moles are present in 98 g of sulfuric acid (H2SO4)? (H=1, S=32, O=16)
Answer
(B)
1.0 moles
13
Which of the following factors might affect the accuracy of a titration?
Answer
A
B
C
14
Which of the following units is used for relative atomic mass?
Answer
(C)
amu
15
What does it mean if a chemical sample is described as being 'pure'?
Answer
(A)
The sample contains only the desired compound.
16
What is the mass of one mole of NaCl?
Answer
(C)
58.5 g
17
What does the relative atomic mass (Ar) represent?
Answer
(B)
The average mass of an atom of an element compared to carbon-12.
18
What is the molar mass of sulfuric acid (H2SO4)? (H = 1, S = 32, O = 16)
Answer
(C)
98 g/mol
19
What is the purpose of the worked examples?
Answer
A
C
20
Which statement best describes what purity means in chemistry?
Answer
(B)
A sample containing only a single substance.
21
What is percentage by mass?
Answer
(A)
The mass of a particular element in a compound.
22
What can cause a reaction yield to be less than 100%?
Answer
A
B
C
23
What is percentage purity?
Answer
(B)
The percentage of pure product in a sample.
24
The relative atomic mass of oxygen is 16. What is the mass of 0.5 moles of oxygen atoms?
Answer
(B)
8 g
25
What are the units for molar volume?
Answer
(A)
L/mol
26
What is the formula for calculating the number of moles?
Answer
(A)
Moles = Mass / Molar Mass
27
Which of the following statements best describes the meaning of the term 'yield' in a chemical reaction?
Answer
(C)
The amount of product obtained.
28
Which of the following statements is correct?
Answer
B
C
29
What can cause a lower actual yield compared to the theoretical yield?
Answer
A
B
C
30
A chemist carries out a reaction and obtains 15 g of a product, even though the theoretical yield was 20g. What is the percentage yield of the reaction?
Answer
(B)
75%
31
How many moles are there in 36 g of water (H2O)? (H=1, O=16)
Answer
(C)
1.5 moles
32
What does the term 'mole' represent?
Answer
(C)
The amount of a substance containing 6.022 x 10^23 particles.
33
What is the relationship between the actual yield, theoretical yield and percentage yield?
