Observation

In part (a), majority of the candidates were able to name three pieces of apparatus that can be used to determine the solubility of a salt.
In part (b), majority of the candidates could not outline the procedure for separating a mixture of sodium chloride and activated charcoal in the laboratory.
In part (c), majority of the candidates could not state two uses of activated charcoal.
In part (d), majority of the candidates were able to state what would be observed when sodium chloride crystals and sodium trioxocarbonate (IV) decahydrate crystals are heated.
In part (e), majority of the candidates could not give reasons why HNO₃ is not used to acidify KMnO4 solution during titrations.
The expected answers include:

1. • Evaporating dish
   • Graduated pipette / burette and funnel
   • Tripod stand with wire gauze
   • Bunsen burner
   • Beaker
   • (Top weighing) chemical balance / Electronic balance / weighing balance
   • Glass rod / stirrer
   • Wash bottle
   • Thermometer
   • Water bath
2. • Add distilled water to the mixture in a beaker, stir to dissolve NaCl
   • Filter the mixture and wash the residue (activated charcoal) with distilled water
   • Dry the residue (activated charcoal) in an oven or between filter paper
   • Evaporate the filterate to concentrate and allow to cool for crystals to form, filter the crystals (NaCl) and dry it in an oven / between filter paper OR Evaporate the filtrate (NaCl) to dryness
3. • To deodorize / remove scent
   • To decolorize
   • To remove suspended particles in a liquid
   • To adsorb gases in a mixture
   • To improve taste of / detoxify / purify water

4. 1.                         NaCl(s) 		-	crackling sound was also accepted
      
      				          -	No change of state / Remains solid
      
                              

   2.                     Na2CO3.10H2O(s)	-	Water vapour given off
      					-	White powder left
      
                              

5. • HNO₃ is a strong oxidizing agent
   • It can oxidize / react with KMnO₄
   • It can also oxidize / react with the substrate.