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HIA International — Grade 8

Unit 1: Photosynthesis and the carbon cycle

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Unit 2: Properties of materials

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Unit 3: Forces and energy

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Unit 4: Maintaining life

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Unit 5: Reactivity

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Unit 6: Sound and space

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Unit 7: Genes and inheritance

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Unit 8: Rates of reaction

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Unit 9: Electricity

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Quiz

Checkpoint Grade 8 Unit 2 – 2.6 Compounds And Formulae

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Compounds And Formulae Checkpoint Chemistry quiz set 2: free practice for Cambridge Checkpoint (chemistry). Work through this Compounds And Formulae Checkpoint Chemistry quiz set 2 and get instant feedback on every answer. If you get stuck, review the 14.6 Compounds and formulae lesson. More practice: Cambridge Checkpoint (chemistry) — all units. Syllabus: Cambridge Lower Secondary programme.

  • Questions count: 50
  • Passing grade: B+
  • Time limit:
Start Quiz
1.
Which statement correctly describes bonding?
a substance made from different elements chemically bonded
symbols and numbers showing the atoms in a substance
a compound represented by the formula NaCl
the joining of atoms by chemical bonds
2.
Which statement correctly describes compound?
the joining of atoms by chemical bonds
symbols and numbers showing the atoms in a substance
a compound represented by the formula NaCl
a substance made from different elements chemically bonded
3.
Which statement correctly describes formula?
the joining of atoms by chemical bonds
a substance made from different elements chemically bonded
a compound represented by the formula NaCl
symbols and numbers showing the atoms in a substance
4.
Which statement correctly describes sodium chloride?
the joining of atoms by chemical bonds
a substance made from different elements chemically bonded
symbols and numbers showing the atoms in a substance
a compound represented by the formula NaCl
5.
Which of these is the FIRST step in the correct order?
count each type of atom
show the bonding
write the formula
identify the symbols
6.
Which step comes immediately after "count each type of atom"?
identify the symbols
write the formula
show the bonding
7.
Which practical work belongs to Compounds And Formulae?
Measure temperature and volume while heating water and identify patterns in results
Model particles physically to represent melting, freezing, evaporation and condensation
Use observations to classify materials and evaluate a particle model
Build simple particle models of compounds and interpret chemical formulae
8.
The pie chart shows what share of the atoms in one particle of compound J are carbon, hydrogen and oxygen. Which formula fits the chart?
Dr Dabour Hub Academy - figure 1
C6H6O6 (equal share)
C12H6O6 (carbon half)
C6H12O6 (glucose)
C6H12O12 (oxygen half)
9.
The box on the left shows the particles of hydrogen and chlorine before they react. All of them react to make hydrogen chloride, HCl. How many HCl particles are in the box on the right?
Dr Dabour Hub Academy - figure 2
Six particles of HCl
Three particles of HCl
Twelve particles of HCl
Two particles of HCl
10.
Electricity is passed through water, splitting it into hydrogen gas and oxygen gas, which collect in tubes A and B. Which tube contains the hydrogen, and why?
Dr Dabour Hub Academy - figure 3
Tube B, because hydrogen is the lighter gas
Tube A, because water has two H atoms for every O atom
Tube B, because water has two O atoms for every H atom
Either tube, because the gases always mix together
11.
Kofi heats green copper carbonate, CuCO3, as shown. A black solid is left and the limewater turns milky. Which statement explains his observations?
Dr Dabour Hub Academy - figure 4
Copper atoms have boiled out and turned the limewater milky
The powder is only melting, so no new substance has formed
Oxygen from the air has joined the limewater to make it milky
The compound has broken down, giving off carbon dioxide
12.
At the end of the experiment in the diagram, Kofi wants to stop heating. What should he do first, and why?
Dr Dabour Hub Academy - figure 5
Lift the delivery tube out of the limewater, so limewater is not sucked back
Turn off the burner first, so the gas stops being made quickly
Pour the limewater away while the tube is still being heated
Put a bung in the test tube of limewater to trap the gas
13.
The graph shows the total number of atoms in one particle of three fuel gases. The next fuel in the series, butane, has 4 carbon atoms and follows the same pattern. What is its formula?
Dr Dabour Hub Academy - figure 6
C4H8 (12 atoms)
C4H12 (16 atoms)
C4H10 (14 atoms)
C4H4 (8 atoms)
14.
Ben counts 8 sodium and 8 chlorine particles in this part of a salt crystal and says the formula should be Na8Cl8. Why is NaCl the correct formula?
Dr Dabour Hub Academy - figure 7
The formula shows only the first two atoms in the crystal
The formula gives the simplest ratio of the atoms, which is 1 : 1
Na8Cl8 would need a bigger crystal than the one drawn
Formulas can only ever contain the number 1
15.
Tariq says: "Sodium chloride is made from sodium and chlorine, so its melting point should be between theirs." What does the bar chart show about his idea?
Dr Dabour Hub Academy - figure 8
It is right: 801 °C lies between 98 °C and –101 °C
It is right: compounds always take the average of their elements
It is wrong: the compound melts lower than both elements
It is wrong: the compound melts far higher than either element
16.
The table lists some compounds used in fertilisers. Which one has the most nitrogen atoms in one particle?
Ammonium nitrate
Ammonia (NH3)
Potassium nitrate
Ammonium chloride
17.
A chemist analysed a sample of rust-coloured iron oxide and counted the atoms of each element. Which formula fits her result?
The formula FeO
The formula Fe3O2
The formula Fe2O3
The formula FeO2
18.
Nadia heated four substances and bubbled any gas through limewater. Which result is most surprising and should be checked, given the substances' formulas?
Calcium carbonate
Sodium chloride
Copper carbonate
Zinc carbonate
19.
Four groups heated copper carbonate and weighed the boiling tube before and after. Which group's result is anomalous?
Group 1 (lost 0.7 g)
Group 2 (lost 0.8 g)
Group 3 (mass rose)
Group 4 (lost 0.7 g)
20.
The table compares hydrogen, oxygen and water. Which piece of evidence best shows that water is a compound and not just the two gases mixed?
Water puts out fires, though hydrogen burns and oxygen helps burning
Water, hydrogen and oxygen are all colourless
Hydrogen boils at a lower temperature than oxygen
Water is found in rivers and seas
21.
Elif tested rock samples to find out which contain calcium carbonate by adding acid and watching for fizzing. Which change would make her test fairer?
Use a different acid for each rock so she can compare acids
Test only the rocks she expects to fizz
Add more acid to the rocks that do not fizz at first
Use the same volume of the same acid on each rock
22.
A molecular model kit contains the balls shown in the table. Kai uses it to build methane particles, CH4. What is the largest number of methane particles he can build at once?
Three particles
Six particles
Twelve particles
Two particles
23.
Compound X2Y has two X atoms for every Y atom. A sample of X2Y contains 50 Y atoms. How many X atoms does it contain?
25 X atoms
50 X atoms
150 X atoms
100 X atoms
24.
Chalk, limestone and marble look different, but all are mostly calcium carbonate, CaCO3. What does the formula tell you about all three?
Each has 3 calcium atoms for every carbon atom
Each has 1 Ca, 1 C and 3 O atoms in a fixed ratio
Each contains a different ratio of the three elements
Each is made of calcium, cobalt and oxygen
25.
Jaya says: "Carbon dioxide, CO2, contains oxygen gas, because it has O2 in its formula." Which is the best reply?
She is right: CO2 is a mixture of carbon and oxygen gas
She is right: the 2 shows a particle of oxygen gas is inside
The two oxygen atoms are each bonded to carbon, not joined as oxygen gas
The 2 means there are two carbon atoms in each particle
26.
A particle of a brown gas contains one nitrogen atom and two oxygen atoms. Which formula should be written for it?
The formula NO2
The formula N2O
The formula NO2O
N1O2 with both numbers
27.
Lena wants to show her class that a compound has different properties from the elements it is made from, using safe school apparatus. Which demonstration plan is best?
Melt some pure iron and show that it is still iron
Dissolve sugar in water and show it can be tasted
Weigh a piece of sulfur before and after cutting it
Test iron, sulfur and the black iron sulfide made from them with a magnet
28.
Each pairing links a compound to an everyday use or place. Which pairing is correct?
Glucose – limestone and chalk
Calcium carbonate – sugar in the blood
Methane – natural gas used as a fuel
Ammonia – fizzy drinks
29.
Each pairing links a formula to the total number of atoms in one particle. Which pairing is correct?
CH4 – 4 atoms
CaCO3 – 3 atoms
C6H12O6 – 18 atoms
NH3 – 4 atoms
30.
Each pairing links a key word to its meaning. Which pairing is correct?
Subscript – the name ending for two elements
Ratio – relative numbers of each type of atom
Molecule – a single atom on its own
Compound – a substance with only one type of atom
31.
Each pairing links an observation to what it shows. Which pairing is correct?
Limewater turns milky – carbon dioxide is present
A black solid forms on heating – no reaction happened
A substance melts – a new compound has formed
Two gases are mixed – a compound must form
32.
Which term is described as: the joining of atoms by chemical bonds?
compound
sodium chloride
bonding
formula
33.
Which term is described as: a substance made from different elements chemically bonded?
bonding
formula
sodium chloride
compound
34.
Which term is described as: symbols and numbers showing the atoms in a substance?
bonding
sodium chloride
formula
compound
35.
Which term is described as: a compound represented by the formula NaCl?
bonding
formula
sodium chloride
compound
36.
Five particles of ammonia, NH3, contain _____ in total.
8 hydrogen atoms
3 hydrogen atoms
5 hydrogen atoms
15 hydrogen atoms
37.
The small number written after a symbol in a formula, like the 2 in H2O, is called a _____.
subscript
prefix word
superscript
chemical symbol
38.
The formula NaCl shows that sodium and chlorine atoms are present in a _____ ratio.
1 : 2 (one to two)
1 : 1 (one to one)
2 : 1 (two to one)
1 : 3 (one to three)
39.
In a compound, the atoms of different elements are held together by _____.
magnetic poles
filter paper
chemical bonds
gravity alone
40.
In glucose, C6H12O6, there are twice as many hydrogen atoms as carbon atoms. True or false?
False – there are 6 of each atom
True – 12 hydrogen atoms and 6 carbon atoms
False – there are twice as many carbon atoms
True, but only in blood sugar
41.
Salt (sodium chloride) can be split back into sodium and chlorine by filtering its solution. True or false?
True – filter paper separates the two elements
True, but only if the water is warm
False – only a chemical reaction can split a compound
False – salt contains no sodium
42.
Using more carbon when making carbon dioxide will change its formula to C2O2. True or false?
False – the ratio in a compound is always fixed
True – the formula depends on how much is used
True, but only when oxygen runs out
False – the formula would become CO3
43.
Methane, CH4, and ammonia, NH3, both have the same total number of atoms in one particle. True or false?
True – both have four atoms
True – both have five atoms
False – ammonia has 5 atoms and methane 4
False – methane has 5 atoms and ammonia has 4
44.
A molecule can be made of atoms of just one element, such as a particle of oxygen gas made of two oxygen atoms. True or false?
True – a molecule is two or more atoms bonded
False – molecules only exist in compounds
False – oxygen gas has no molecules
True, but only for metals
45.
When hydrogen burns in oxygen, the water made still burns like hydrogen and helps burning like oxygen. True or false?
True – a compound keeps its elements' properties
True, but only while the water is hot
False – water has new properties of its own
False – no water is made at all
46.
A large balloon of carbon dioxide has more oxygen atoms in each particle than a small balloon of carbon dioxide. True or false?
True – more gas means more atoms per particle
False – every particle is CO2 with two O atoms
True, but only if it is squeezed
False – the small balloon has more per particle
47.
Limewater turning milky is the test for carbon dioxide gas. True or false?
False – it is the test for oxygen
False – it is the test for hydrogen
True, but only for oxygen as well
True – the statement is correct
48.
In chalk, CaCO3, there are more oxygen atoms than calcium and carbon atoms added together. True or false?
True – 3 oxygen atoms but only 2 of the others
False – there are 3 calcium atoms
False – there are equal numbers of each
True, but only in marble
49.
When heating copper carbonate, reheating and reweighing until the mass stops changing helps to show that all of it has reacted. True or false?
False – the mass never changes when heating
False – reheating makes more copper carbonate
True – a constant mass shows no more gas is lost
True, but only if the tube is sealed
50.
A compound whose name ends in -ide, such as sodium chloride, can never contain oxygen. True or false?
True – -ide means no oxygen at all
False – oxides such as CO2 end in -ide
True, but only for sodium compounds
False – -ide means three elements
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Part of Unit 2: Properties of materials — see every lesson and quiz in this unit.
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