Chemistry 0620 · IGCSE · Simple molecules and covalent bonds

Simple molecules and covalent bonds — practice question

A formula list appears below. AlCl$_3$ CaCO$_3$ CO CO$_2$ CoCl$_2$ CuSO$_4$ MgCl$_2$ N$_2$ NaCl NH$_3$ O$_2$ SO$_2$ Use these formulae to answer the questions that follow. Each formula can be chosen once, several times or not chosen at all. State which formula represents:
(a(i))[1]

a compound that turns from white to blue when water is added

(a(ii))[1]

a compound that is used in the manufacture of cement

(a(iii))[1]

an element that makes up 78% of clean, dry air

(a(iv))[1]

a compound that contains an ion with a single positive charge

(a(v))[1]

a compound that dissolves in water to make an alkaline solution

(b)[2]

Complete the dot-and-cross diagram to show how electrons are arranged in one molecule of ammonia.

(c)[1]

State whether magnesium oxide is a basic oxide or an acidic oxide. Explain your answer.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: CuSO4

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