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Course: HIA International — Grade 8
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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

2.4 Simple and Giant Structures

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Simple and Giant Structures HIA Science quiz set 2: free practice for HIA International. Work through this Simple and Giant Structures HIA Science quiz set 2 and get instant feedback on every answer. If you get stuck, review the 20.11 Simple and Giant Structures – Notes lesson. More practice: HIA International — all units. Syllabus: Cambridge Lower Secondary programme.

  • Questions count: 50
  • Passing grade: A-
Start Quiz
1.
What is a simple molecular structure?
Small separate molecules
A continuous metal lattice
Positive ions only
One giant atom
2.
What is a giant structure?
Billions of atoms or ions joined in a repeating arrangement
One small molecule
A mixture of unbonded gases
A single nucleus
3.
What does the word lattice mean?
A regular repeating arrangement of particles
A random collection of molecules
A moving stream of electrons
A single covalent bond
4.
What holds separate simple molecules near one another?
Weak intermolecular forces
Metallic bonds
Nuclear forces
Strong ionic bonds inside every molecule
5.
Why do many simple molecular substances have low melting points?
Only weak forces between molecules must be overcome
Their nuclei are removed easily
All their covalent bonds are weak
They contain free ions
6.
During melting of a simple molecular substance, what is mainly overcome?
Forces between molecules
Protons inside nuclei
Covalent bonds within each molecule
The atoms themselves
7.
Why does carbon dioxide have a very low melting point?
Its small molecules separate when weak intermolecular forces are overcome
It contains mobile ions
Its carbon atoms form metal layers
It has no covalent bonds
8.
Which is an example of a simple molecular substance?
Water
Diamond
Graphite
Sodium chloride lattice
9.
What particles occupy a giant ionic lattice?
Positive and negative ions
Neutral molecules only
Free protons and neutrons
Carbon layers only
10.
Why does solid sodium chloride not conduct electricity?
Its ions are fixed in the lattice
It contains no charged particles
Its electrons have no energy
It is made of molecules
11.
The diagram shows the particles in four different substances, A to D. Which substance is most likely to be a gas at room temperature?
Dr Dabour Hub Academy - figure 1
Substance A
Substance B
Substance C
Substance D
12.
Farida measured or looked up the melting points of six unknown substances, J to O, shown in the bar chart. Using the melting points, how many of the substances are most likely to have giant structures?
Dr Dabour Hub Academy - figure 2
Two – K and M only
Three – K, M and O
Four – K, L, M and O
Five – all except J
13.
Rania sets up the circuit shown and the lamp lights. Which single change to the apparatus would make the lamp go out?
Dr Dabour Hub Academy - figure 3
Dissolve twice as much salt in the same water
Replace both carbon rods with copper rods
Replace the salt solution with sugar solution
Warm the salt solution to about 40 °C
14.
Suleiman heats a white solid in a boiling tube held in an oil bath and records its temperature every minute. Which conclusion is best supported by his graph?
Dr Dabour Hub Academy - figure 4
It is a mixture, because the temperature stops rising for a while
It is giant ionic, because it has one fixed melting point
It is giant covalent, because it took five minutes to melt
It is a pure substance with a simple molecular structure
15.
The diagram shows part of the structure of graphite, a form of carbon. Y is a strong bond between two atoms in a layer. X is the gap between two layers, where the forces are weak. Which use of graphite depends mainly on the forces at X being weak?
Dr Dabour Hub Academy - figure 5
Making the marks of a pencil on paper
Making electrodes that must not melt
Making cutting tools that stay sharp
Making crucibles for melting metals
16.
Kofi hits a crystal of an ionic compound with a hammer and it shatters. The diagram shows the ions before and after the blow moves the top layers. Which statement best explains why the crystal breaks apart?
Dr Dabour Hub Academy - figure 6
The blow breaks the ions into smaller separate molecules
The layers slide easily because no forces act between them
Ions of the same charge end up side by side and repel
The ions lose their charges and stop attracting each other
17.
Use the table of properties. Which substance is most likely to have a giant ionic structure?
Substance Q
Substance S
Substance T
Substance R
18.
Grace has three unlabelled white powders: sand, sugar and table salt. Her test results are in the table. Which row matches sugar, and why?
Powder 2 – low melting point and a non-conducting solution
Powder 1 – it does not dissolve, like most molecules
Powder 3 – it dissolves and forms charged molecules
Powder 3 – it has the highest melting point that dissolves
19.
Use the table. Which substance is a liquid at a room temperature of 25 °C?
Chlorine – it melts well below 25 °C
Bromine – 25 °C is between its melting and boiling points
Iodine – it boils at under 200 °C
Silicon dioxide – it melts in a warm room
20.
Dev places 1 g samples at different spots on a metal lid above a Bunsen flame and times how long each takes to melt (see table). Which variable must he control to make this a fair test?
The time taken for each sample to melt
The type of solid placed on the lid
Each sample's distance from the flame
Whether each sample melts at all
21.
Mei passes a current through molten potassium iodide four times with the same apparatus. Which is the most likely reason for the result in trial 3?
The substance had started to solidify
Potassium iodide is simple molecular
The ions moved faster in trial 3
Molten ionic substances conduct poorly
22.
Nadia compares diamond and graphite using the table. Which conclusion is best supported by the data?
Graphite must contain a metal that makes it conduct
Graphite has weaker bonds, so it melts at a lower temperature
How the atoms are arranged affects the properties
Diamond is harder because it contains more types of atom
23.
A jeweller explains that a diamond will not melt in an ordinary fire. Which explanation of the very high melting point of diamond is correct?
Its molecules are tightly packed but have weak forces
Its ions have strong charges that attract each other
Its atoms are too heavy to move when heated
Many strong bonds throughout must all be broken
24.
Graphite is used for the electrodes in some batteries. Why can graphite conduct electricity when diamond cannot?
Graphite has electrons that are free to move
Graphite contains ions that move between layers
Graphite has weaker bonds between its carbon atoms
Graphite contains a small amount of metal
25.
An electrician bends a copper wire into a loop without it snapping, and the same wire carries current to a lamp. Which description of copper's structure explains both properties?
Simple molecules held by weak forces
A giant lattice of metal atoms with free electrons
A giant ionic lattice of + and − ions
A giant covalent network with no free electrons
26.
Lucas plans to heat small samples of wax, sulfur and salt in test tubes over a Bunsen burner to compare how easily they melt. Which precaution is most important for his safety?
Use larger samples so the results are clearer
Hold the test tubes firmly in his bare hand
Heat in a fume cupboard and wear eye protection
Point each test tube towards his partner
27.
In a lesson, students decide whether solids are simple or giant by watching whether they "melt quickly" on a hot plate. Which improvement would give the most reliable evidence?
Use a stopwatch without measuring temperature
Test one sample only to save time
Ask each student to guess the melting point
Measure each melting point with a thermometer
28.
Jin predicts: "Substances with giant structures never dissolve in water." Which result from his class would show the prediction is wrong?
Sodium chloride dissolves easily in water
Sand stays at the bottom of the beaker
A diamond does not dissolve in water
Sugar dissolves but does not conduct
29.
Drill bits for cutting through rock often have tiny diamonds fixed to their tips. Which property of diamond's giant structure makes it suitable?
It conducts electricity well
It is extremely hard and wears slowly
It has a very low melting point
It is soft and slippery
30.
A crystal of table salt seen under a hand lens has flat faces and a cube shape. Why do sodium chloride crystals grow with such a regular shape?
The salt molecules are shaped like tiny cubes
Water molecules stay inside each crystal
The ions stack in a repeating pattern
Sodium and chlorine atoms are mixed randomly
31.
Four substances are each paired with a type of structure. Which pairing is correct?
Diamond (C) – simple molecular
Methane (CH₄) – simple molecular
Sodium chloride (NaCl) – giant covalent
Water (H₂O) – giant ionic
32.
Each material is paired with a use and a reason. Which pairing is correct?
Diamond – electrical wiring, as it conducts
Iodine – furnace lining, as it melts very high
Graphite – dry lubricant, as its layers slide
Salt crystal – drill tips, as it is very hard
33.
Each observation is paired with an explanation. Which pairing is correct?
Iodine melts easily – bonds inside its molecules break
Diamond is very hard – its molecules are packed closely
Solid salt does not conduct – it contains no charged particles
Molten salt conducts – its ions are now free to move
34.
A class uses tests to decide whether an unknown solid is simple molecular or giant. Each test is paired with what its result shows. Which pairing is correct?
Melting point above 1000 °C – points to a giant structure
Solid dissolves in water – proves it is simple molecular
Solid is white – shows it has a giant ionic lattice
Solution does not conduct – proves it is giant covalent
35.
In a giant covalent structure such as diamond, every atom is joined to its neighbours by strong _____, so there are no separate molecules.
weak attractive forces
covalent bonds between atoms
positive and negative ions
free-moving electrons
36.
Graphite is used for electrodes in the industrial extraction of metals because it conducts electricity and has a very high _____.
solubility
molecule size
melting point
hardness
37.
Omar tests solutions of salt, sugar and copper sulfate with the same circuit to see which conduct. In his test the independent variable is the _____.
brightness of the lamp
voltage of the cell
volume of the water
substance dissolved
38.
Sugar dissolves in water, but the solution does not conduct electricity because sugar is made of _____, which carry no electric charge.
neutral molecules
positive ions
free electrons
a giant ionic lattice
39.
A teacher demonstrates heating sodium chloride between two electrodes connected to an ammeter. Statement: "The graph shows that solid sodium chloride conducts better and better as it is warmed from 20 °C to 700 °C." True or false?
Dr Dabour Hub Academy - figure 7
True – the current rises steadily with temperature
False – the current stays at zero until it melts
True – heating frees ions all through the solid
False – the current falls as the solid warms
40.
Ahmed studies the scratch-test table and concludes: "All substances with giant covalent structures are very hard." True or false?
True – diamond and quartz scratch everything
True – strong bonds always make a solid hard
False – quartz is simple molecular, not giant
False – graphite is giant covalent but soft
41.
Using the table, Nour says: "Every substance made of simple molecules is a gas at room temperature." True or false?
True – all four elements are made of small molecules
False – bromine and iodine are also simple molecules
True – the forces between molecules are always weak
False – iodine is solid, so it cannot be molecular
42.
Statement: "When water boils in a kettle, the water molecules split up into hydrogen and oxygen gases." True or false?
False – steam is still water molecules
True – boiling breaks the bonds in H₂O
True – bubbles show that oxygen is released
False – steam is made of hydrogen gas only
43.
Carbon dioxide (CO₂) is a gas but silicon dioxide (SiO₂, sand) is a solid that melts at 1710 °C. Statement: "The difference is because carbon dioxide is made of small separate molecules while silicon dioxide is a giant structure." True or false?
False – silicon is a metal, so sand is ionic
True – that explains the difference
False – both are giant structures of atoms
False – sand is heavier, so it cannot evaporate
44.
A new material melts at 1600 °C and does not conduct electricity either as a solid or when molten. Statement: "It most likely has a giant covalent structure." True or false?
False – it must be ionic as it melts so high
False – it must be simple molecular as it never conducts
True – high melting point, never conducts
True, but only if it also dissolves in water
45.
Statement: "Diamond and graphite have different properties because they are made of different elements." True or false?
True – diamond is carbon, graphite is lead
True – graphite contains extra metal atoms
False – both are compounds of carbon
False – both are made only of carbon atoms
46.
Statement: "Salt solution conducts electricity because dissolved salt forms charged molecules that move through the water." True or false?
False – it is separate ions, not molecules, that move
True – salt forms charged molecules
True – the water molecules carry the charge
False – salt solution does not conduct
47.
Statement: "Magnesium oxide is used to line the inside of furnaces because its giant ionic lattice gives it a very high melting point." True or false?
False – it is used because it conducts heat
True – strong forces act between its ions
False – ionic substances melt at low temperatures
True, because its molecules are very large
48.
Leila finds that her sample of a solid melts gradually between 140 °C and 155 °C. Statement: "This proves the sample has a giant structure." True or false?
True – anything above 100 °C is giant
True – giant structures melt gradually
False – a range means it is impure
False – giant structures cannot melt at all
49.
Statement: "Diamond conducts electricity well because its carbon atoms are joined by very strong bonds." True or false?
True – strong bonds let charge flow
True – every carbon atom is charged
False – diamond is made of molecules
False – none of its electrons are free to move
50.
Candle wax is made of large simple molecules. Statement: "Candle wax does not conduct electricity either as a solid or as a liquid." True or false?
True – its molecules carry no charge
False – molten wax conducts like molten salt
False – solid wax conducts due to its lattice
True, but only because wax is too soft
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Part of Unit 2: Properties of materials — see every lesson and quiz in this unit.
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