CIE iGCSE Co-Ordinated Science C7.2 Oxides Exam Style Questions Paper 3
Question
(a) The list gives the names of six compounds.
aluminium oxide
ammonium nitrate
carbon dioxide
lead bromide
sodium chloride
sulfur dioxide
Answer the questions about these compounds.
Each compound may be used once, more than once or not at all.
State which compound:
(i) has the formula PbBr2.
(ii) is a salt from which ammonia can be displaced.
(iii) is an acidic oxide.
(iv) is a greenhouse gas.
(v) is the main constituent of bauxite.
(b) Aluminium, copper and iron are all solid metals.
State three general physical properties of solid metals.
1 …………………………………………………………………………
2 …………………………………………………………………………
3 …………………………………………………………………………
(c) (i) Duralumin is an alloy of aluminium.
Table 2.1 shows the percentage composition of duralumin.
Calculate the mass of aluminium in 20 kg of duralumin.
mass of aluminium = ……………………………………………. kg
(ii) Table 2.2 shows the melting points of aluminium, copper, magnesium and duralumin.
Duralumin does not have a precise melting point but melts over a range of temperatures.
Explain why duralumin does not have a precise melting point.
▶️Answer/Explanation
Ans : 2(a)(i) lead bromide ;
2(a)(ii) ammonium nitrate ;
2(a)(iii) carbon dioxide / sulfur dioxide ;
2(a)(iv) carbon dioxide ;
2(a)(v) aluminium oxide ;
2(b) any three from:
conducts heat ;
conducts electricity ;
malleable ;
high melting/boiling point ;
2(c)(i) 95 / 100 × 20 = 19 (kg) ;
2(c)(ii) because it is not a pure substance / it is a mixture ;
Question
(a) An atom of copper has a proton number of 29 and a nucleon number of 63.
(i) State the number of electrons in this copper atom. …………………………….
(ii) State the number of neutrons in this copper atom. …………………………….
(b) Copper oxide is heated with carbon. Copper and carbon dioxide are made.
(i) Write the word equation for this reaction.
(ii) In this reaction, reduction of copper in the copper oxide occurs.
Describe what is meant by the term reduction.
…………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(iii) Explain why copper oxide is described as a basic oxide.
…………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(c) Copper is a transition element.
Transition elements have high densities, high melting points and high boiling points. They are all metals.
State one other property of a transition element.
……………………………………………………………………………………………………………………..
……………………………………………………………………………………………………………………..
(d) (i) Brass is a mixture of copper and zinc.
State the term used to describe a mixture of metals.
…………………………………………………………………………………………………………………….
(ii) Brass is more malleable than either copper or zinc.
State the meaning of the term malleable.
…………………………………………………………………………………………………………………….
(iii) State the symbols of both copper and zinc.
copper symbol ……………………
zinc symbol ……………………
(e) A metal key is covered with a layer of copper by electroplating.
(i) The key is an electrode.
State which electrode is the key.
…………………………………………………………………………………………………………………….
(ii) Suggest a suitable electrolyte for electroplating the key.
…………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 8(a)(i) 29 ;
8(a)(ii) 34 ;
8(b)(i) copper oxide + carbon → copper + carbon dioxide ;
8(b)(ii) loss of oxygen ;
8(b)(iii) metal oxide / reacts with an acid to make a salt / neutralises an acid ;
8(c) any one from:
forms coloured compounds ;
acts as catalyst ; variable valency ;
8(d)(i) alloy ;
8(d)(ii) can be beaten into shape;
8(d)(iii) Cu and Zn ;
8(e)(i) cathode / negative ;
8(e)(ii) copper (II) sulfate ;