Year 10 Advanced Science – Trial Chemistry Test 2016 (ANSWERS)
1. C 2. D 3. C4. C 5. D 6. A 7. B 8. B 9. D 10. C
11. B 12. B 13. B14. D 15. D16. A 17. C 18. A 19. B 20. C
2. Mg1212(2,8,2)
Calcium2020 (2,8,8,2)
PhosphorusP1531
Ne1010(2,8)
Aluminium ion1314(2,8)
Fe2630
S2-1616(2,8,8)
3. a) Sodium bromideionic 2
b) Silver oxideionic 3
c) Watercovalent 3
d) Ammonium sulphateionic 15
e) Phosphoruscovalent 4
4 a) NaNO3b) Na2Oc) NH4Cld) MgF2
e) ZnSO4f) Fe2O3g) FeSh) Al2(CO3 )3
5. Balancing Equations(corrected)
a) 1212
b) 432
c) 1211
d) 1111
e) 2112
6. See opposite page
7. a) NaOH Sodium hydroxide - having OH- ions
b) HNO3 Nitric acid – having H+ ions
c) Neutralisation reaction
d) salt and water
HNO3 + NaOH NaNO3 + H2O
8. a) Combinationb) Precipitation c) Combustion
d) decompositione) Displacement
9. a) 4Fe + 3O2 2 Fe2O3
b) water/ moisture, acid, high temperature, salt
c) oil/ grease, covering with plastic, drying (agent), electroplating or galvanization
10. Similarities: Both involve valency electrons in bond formation/
Both involve non-metal
Differences: Ionic compounds involve metal and non-metal compared to only non-metals in covalent compounds/
Ionic compounds involve the donation of electrons by metal atom and receiving electrons by non-metallic atom. However, electrons are shared by non-metallic atoms in covalent compound./
Ionic compounds have much higher melting point compared to that in covalent compounds/
Ionic compounds have free ions in molten or aqueous state but no free ions from covalent compounds.
11. a) The ionic lattice arrangement bound both Na+ and Cl- ions in 3 dimensional manner, it is very difficult to break these bonds unless at a rather high temperature over 800oC
b) When it is molten at high temp, or when it is dissolved in water, the bonds are broken, free Na+ and Cl- ions are available to conduct electricity.
c) The metal atoms are packed tightly together with their valency electrons moving freely among them, allowing electricity to pass through in a closed circuit.
12. a) K – most active Au - least active - Gold is at the end of the reactivity series, it is rather unreactive to oxygen, acid and water
b) Aluminium
c) They are metals that are not active and can exist as metals themselves, including Ag, Au and Cu
d) Zinc is more active, it will oxidise to form Zinc oxide, protecting the underlying iron or steel from rusting, however, copper is less active and can’t protect iron at all.
e) They are far too active that can react with air/oxygen and water, hence they are stored in oil to prevent contact with air and water. Reasons: Either K or Na has only one valence electron, this electron is readily and easily to leave the atom and received by non-metals to form ionic compounds.
f) Silver is the best conductor of electricity, however, it is very expensive and too soft.