Grade-7 Unit-4 (Bonding) Revision Questions

Which diagram represents the structure of solid sodium chloride?

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How many electrons are used to form covalent bonds in a molecule of methane, CH₄?

• 2

• 4

• 6

• 8

Magnesium oxide has a high melting point.

Carbon dioxide has a low melting point.

Which choice identifies the attractive forces that are broken when these compounds are melted?

• magnesium oxide: strong attractions between molecules

  carbon dioxide: weak attractions between atoms

• magnesium oxide: strong attractions between molecules

  carbon dioxide: weak attractions between molecules

• magnesium oxide: strong attractions between ions

  carbon dioxide: weak attractions between atoms

• magnesium oxide: strong attractions between ions

  carbon dioxide: weak attractions between molecules

What is the formula of calcium bromide?

• CaBr

• Ca₂Br

• CaBr₂

• Ca₂Br₂

What is the name of Fe₂S₃ ?

• Iron (IV) sulfide

• Iron (I) sulfide

• Iron (III) sulfide

• Iron (II) sulfide

Lithium reacts with fluorine to form the compound lithium fluoride.

Which statement about this reaction is correct?

• Each fluorine atom gains one electron.

• Each fluorine atom gains two or more electrons.

• Each fluorine atom loses one electron.

• Each fluorine atom loses two or more electrons.

Ammonia, NH₃, is a covalent molecule.

Which diagram shows the outer shell electron arrangement in a molecule of ammonia?

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Solid X has a high boiling point.

Its structure has positive ions surrounded by a sea of electrons.

Which other properties does solid X have?

• brittle and an electrical conductor

• brittle and an insulator

• malleable and an electrical conductor

• malleable and an insulator

The formulae of some ions are shown.

In which row is the formula not correct?

• Compound: aluminium oxide

  Formula: Al₂O₃

• Compound: iron(II) nitride

  Formula: Fe₂N₃

• Compound: sodium sulfate

  Formula: Na₂SO₄

• Compound: zinc nitrate

  Formula: Zn(NO₃)₂

Which row describes the structure of the positive ion in sodium chloride?

• protons: 11

  electrons: 11

  neutrons: 12

• protons: 11

  electrons: 10

  neutrons: 12

• protons: 17

  electrons: 17

  neutrons: 18

• protons: 17

  electrons: 18

  neutrons: 18