Question 1
How is an ionic bond formed?
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By attraction between oppositely charged ions
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By sharing pairs of electrons between atoms
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By attraction between neutral molecules
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By proton transfer between non-metals
Question 2
What is the formula of magnesium oxide formed from Mg2+ and O2-?
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MgO
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Mg2O
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MgO2
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Mg2O3
Question 3
Why do ionic compounds usually have high melting points?
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Strong attractions act throughout a giant ionic lattice
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They contain weak intermolecular forces
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Ionic bonds break easily at low temperatures
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Ions are not bonded in the solid state
Question 4
Why does solid sodium chloride not conduct electricity?
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Its fixed ions cannot carry charge
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It has no charged particles
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Its electrons are free to move
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Sodium chloride has covalent bonding
Question 5
When does sodium chloride conduct electricity?
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When molten or dissolved in water
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When solid
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When cooled below room temperature
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As a gas
Question 6
What is a covalent bond?
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A shared pair of electrons between atoms
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A transferred pair of protons
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An attraction between positive metal ions
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A force between ions in solution
Question 7
Why do simple molecular substances like CO2 often have low boiling points?
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Weak intermolecular forces are overcome on boiling
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Covalent bonds inside molecules are weak
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Their molecules are ionic lattices
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They contain no electrons
Question 8
What type of structure does diamond have?
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A giant covalent structure where each carbon bonds to four others
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Layers of carbon with weak forces between layers
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A giant ionic lattice of carbon ions
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Small molecules with weak forces
Question 9
Why can graphite conduct electricity?
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It has delocalised electrons that can move through the structure
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It contains mobile ions in the solid
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Each carbon atom has no outer electrons
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It is made of metallic bonds
Question 10
Why is graphite soft and slippery?
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Its layers can slide because weak forces act between layers
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Its covalent bonds are weak within each layer
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It has no bonds between carbon atoms
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It is a liquid at room temperature
Question 11
Which statement about graphene is correct?
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It is a single carbon layer that conducts electricity
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It is a gas made of C60 molecules
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It is an ionic compound of carbon and oxygen
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It is an insulator because it has no electrons
Question 12
What best describes metallic bonding?
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Attraction between positive metal ions and delocalised electrons
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Attraction between neutral metal atoms
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Sharing electron pairs between metal and non-metal atoms
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Attraction between negative ions and protons
Question 13
Why are metals good conductors of electricity?
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Delocalised electrons are free to move through the metal
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Metal ions can leave the lattice in the solid state
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Metals contain free protons that move
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Metals are made of simple molecules
Question 14
Why are alloys usually harder than pure metals?
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Different-sized atoms distort layers and make sliding harder
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Different atoms create gaps that help layers slide
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Mixed atoms remove the delocalised electrons
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Mixed atoms arrange the layers more regularly
Question 15
Which substance has a giant covalent structure?
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Silicon dioxide (SiO2)
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Methane (CH4)
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Oxygen (O2)
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Hydrogen chloride (HCl)
Question 16
What size range defines nanoparticles?
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About \(1\text{ to }100\,\mathrm{nm}\)
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About \(1\text{ to }100\,\mathrm{mm}\)
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About \(1\text{ to }100\,\mathrm{\mu m}\)
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About \(1000\text{ to }10{,}000\,\mathrm{nm}\)
Question 17
Why are nanoparticles often more reactive than larger particles of the same substance?
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They have a larger surface-area-to-volume ratio
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Their atoms contain more protons
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Their chemical bonds become stronger as size falls
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Their smaller surface gives fewer collisions
Question 18
What is one concern about widespread nanoparticle use?
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Possible health or environmental effects may be uncertain
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Bulk-material tests are assumed to predict their effects
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Small size is assumed to stop entry into cells
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Low mass is assumed to make them unreactive
Question 19
Which statement about polymers is correct?
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Long-chain molecules made from repeating units
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Giant lattices made from alternating ions
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Metal ions surrounded by delocalised electrons
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Small molecules joined by temporary intermolecular forces
Question 20
Why does iodine (I2) have a much lower boiling point than sodium iodide (NaI)?
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I2 has weak intermolecular forces; NaI has strong ionic attractions
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I2 has weak ionic attractions; NaI has strong covalent bonds
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I2 has strong intermolecular forces; NaI has weak ionic attractions
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Both have identical bonding; NaI simply has greater relative mass
Question 21
Why do ionic compounds conduct electricity when dissolved?
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Their ions are free to move
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Their electrons move between ions
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Their covalent bonds break into protons
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Their ions become neutral atoms
Question 22
Why is diamond hard?
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Each carbon atom forms four strong covalent bonds
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It has weak forces between molecules
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Its ions are free to move
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It contains delocalised electrons
Question 23
How can nanoparticles be useful in drug delivery?
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They can carry medicine to target tissues
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They spread medicine throughout the body without targeting
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They release medicine before reaching the target
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They prevent medicine entering target cells
Question 24
Why do nanoparticles have different properties from bulk materials?
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They have a very high surface area to volume ratio
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They contain different elements
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They have more atoms per particle
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They are gases at room temperature
Question 25
What is a simple molecular substance made of?
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Small covalent molecules
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A giant ionic lattice
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A giant metallic lattice
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A network of mobile ions
Question 26
Why do polymers have a wide range of properties?
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Their structures and intermolecular forces can vary
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All polymers have identical chain lengths
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They contain no covalent bonds
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All polymers are metals
Question 27
Why do many metals have high melting points?
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Strong attraction links ions and delocalised electrons
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Weak forces act between separate metal molecules
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Metal ions move freely through the solid lattice
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Covalent bonds join each pair of metal atoms
Question 28
Why are metals malleable?
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Layers of atoms can slide while metallic bonding remains
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Their ions shatter when layers move
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Their atoms are joined by weak covalent bonds
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Their electrons are fixed between atoms
Question 29
What shape is a C60 fullerene molecule?
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Hollow sphere
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Flat sheet
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Straight chain
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Giant cubic lattice
Question 30
Why is graphene useful in electronics?
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It conducts electricity and is very strong
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It conducts electricity but breaks under small forces
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It is strong but lacks mobile charge carriers
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It is flexible but dissolves in water