Question 1:
Diagram 1.1 shows an experiment for a type of pure metal and alloy.
(a) Based on the experiment,
(i) state one manipulated variable [1 mark]
(ii) state one observation after four weeks on test tube P [1 mark]
(iii) state one inference on the observation in 1(a)(ii). [1 mark]
(b) Diagram 1.2 shows test tube P after being left for eight weeks.
State the relationship between the number of days and the amount of brown precipitate on the iron ring. [1 mark]
(c) The following statement shows a conclusion for the experiment.
Based on Diagram 1.1, state one evidence that shows the conclusion is accurate. [1 mark]
Answer:
(a)(i) Type of the ring (iron ring and steel ring)
(ii) After four weeks, iron ring in test tube P showed a brown layer formed on the surface of the iron ring.
(iii) The brown layer and precipitate that formed around and on the surface of the iron ring in test tube P indicates that the oxidation/rusting process has occurred on the iron ring.
(b) The longer the iron ring is exposed to water and air, the more brown precipitate is formed.
(c) No changes occurred on the steel ring in test tube Q after four weeks, while the iron ring in test tube P showed a brown layer.
Diagram 1.1 shows an experiment for a type of pure metal and alloy.
(a) Based on the experiment,(i) state one manipulated variable [1 mark]
(ii) state one observation after four weeks on test tube P [1 mark]
(iii) state one inference on the observation in 1(a)(ii). [1 mark]
(b) Diagram 1.2 shows test tube P after being left for eight weeks.
State the relationship between the number of days and the amount of brown precipitate on the iron ring. [1 mark]
(c) The following statement shows a conclusion for the experiment.
Based on Diagram 1.1, state one evidence that shows the conclusion is accurate. [1 mark]
Answer:
(a)(i) Type of the ring (iron ring and steel ring)
(ii) After four weeks, iron ring in test tube P showed a brown layer formed on the surface of the iron ring.
(iii) The brown layer and precipitate that formed around and on the surface of the iron ring in test tube P indicates that the oxidation/rusting process has occurred on the iron ring.
(b) The longer the iron ring is exposed to water and air, the more brown precipitate is formed.
(c) No changes occurred on the steel ring in test tube Q after four weeks, while the iron ring in test tube P showed a brown layer.