Types of substances

Question 1

(ii) Magnesium oxide has a melting point of 2852°C.
Explain why magnesium oxide has such a high melting point.
(3)

Answer 1

An explanation that combines identification – knowledge
(1 mark) and reasoning/justification – understanding (2
marks):
• very strong bonds/ionically bonded (1)
• between 2+ cations and 2– anions (1)
• so requires lot of energy to separate magnesium and oxide
ions to melt the solid (1)

Question 2

Carbon dioxide can be formed by the reaction of calcium carbonate, CaCO3
,
with dilute hydrochloric acid.
Write the balanced equation for this reaction.
(3)

Answer 2

CaCO3 + 2HCl → CaCl2 + H2O

+ CO2

Question 3

(ii) Copper forms coloured compounds.
Give the name of the type of metals that form coloured compounds.
(1)

Answer 3

transition (metals/ elements)