Page 46 - Spotlight A+ Form 4 & 5 Chemistry KSSM

Which of the following are correct about the Which of the following are the oxidising agent
compound? and reducing agent in the reaction?
I Low melting point Oxidising agent Reducing agent
II Exist as liquid at room temperature.
III Double covalent bond formed in the A Fe O 3 C
2
compound. B C Fe O
2
IV Conduct electricity in solid state. C Fe CO 3
A I and III 2
B I and IV D CO 2 Fe
C II and III
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D III and IV 20. The equation below shows the reaction between
17. Figure 6 shows the reaction between calcium excess zinc carbonate, ZnCO with dilute
3
carbonate, CaCO and glacial ethanoic acid, hydrochloric acid, HCl.
3
CH COOH. ZnCO (s) + 2HCl(aq) → CaCl (aq) + CO (g) +
3
2
Glacial ethanoic acid, 3 2 H O(l)
CH COOH 2
3
The changes of the quantity of reactants and
products are recorded with time until the
reaction is completed. Which graph shows the
correct changes?
Limewater
A Mass of zinc carbonate, ZnCO (g)
3
SPM MODEL PAPER No changes are observed after the reaction. What Time (s)
Calcium carbonate, CaCO
3
Figure 6
should be done in order to make the limewater
cloudy?
A Heat the mixture.
B Add water to the mixture.
2
C Substitute calcium carbonate, CaCO with
–3
solution (mol dm )
magnesium, Mg powder. 3 B Concentration of calcium chloride, CaCl
D Change calcium carbonate, CaCO chips to
3
calcium carbonate, CaCO powder.
3
18. Bronze is an alloy which contains copper and tin
atoms. In an activity, Shahriza found that bronze Time (s)
is harder than pure copper. Which statement
explains the situation above? C Concentration of hydrochloric acid, HCl (mol dm )
–3
A Tin atom makes strong bonds between the
pure copper atom.
B Tin atom fills in all the empty spaces
between pure copper atom.
C Tin atom compresses the arrangement of Time (s)
atom in pure copper.
D Tin atom reduced the layer of pure copper
atoms from sliding. D Volume of carbon dioxide, CO (cm )
3
2
19. The following equation represents a redox
reaction.
2Fe O + 3C → 4Fe + 3CO
2 3 2
Time (s)

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