COMBINED SCIENCE Paper 2 (Core)
October/November 2010 1 hour 15 minutes
Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. A copy of the Periodic Table is printed on page 20. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner's Use 1 2 3 4 5 6 7 8 9 Total
This document consists of 20 printed pages.
IB10 11_0653_21/4RP © UCLES 2010
2 1 (a) State the word equation for photosynthesis.
For Examiner's Use
(b) (i) Name the green pigment found in plant leaves which absorbs energy from sunlight.  (ii) Fig. 1.1 is a diagram of a plant cell. On the diagram, draw a label line to where this green pigment would be found, and label it P.
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3 (c) A student fixed a piece of black paper over a leaf, which was still attached to the plant. He left the plant in the sun for two days. He then removed the leaf from the plant and tested it for starch, after removing the paper. (i) Using the letters given, list the correct sequence of the steps he took. A Add iodine solution to the leaf. For Examiner's Use
Place the leaf in boiling water.
Dip the leaf into water to soften it.
Place the leaf in hot ethanol.
Spread the leaf on a white tile. 
(ii) Fig. 1.2 shows the leaf before and after he did the starch test.
Fig. 1.2 Iodine solution is orange-brown. It turns blue-black when it is in contact with starch. Complete the diagram of the leaf after testing in Fig. 1.2. Do not colour the diagram. Use labels to show which parts would look orange-brown and which parts would look blue-black. 
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4 2 Fig. 2.1 shows the apparatus a student used to measure the rate of reaction between some powdered metal and dilute hydrochloric acid. For Examiner's Use
test-tube full of water conical flask 1.0 g powdered metal dilute hydrochloric acid water
Fig. 2.1 When the student tilted the conical flask, the acid mixed with the powdered metal. If a reaction occurred, any gas which was produced bubbled up into the test-tube, pushing the water out. The student timed how long it took for the test-tube to fill with gas. (a) Describe how the student could test the gas to show that it was hydrogen.
(b) The student used the apparatus in Fig. 2.1 to compare the rates of reaction between dilute hydrochloric acid and three powdered metals, X, Y and Z. The results the student obtained are shown in Table 2.1. Table 2.1 metal mass of metal / g X Y Z 1.0 1.0 1.0 time for gas to fill the test-tube / seconds 150 45 no gas was produced
(i) One of the metals used was copper. State and explain which metal, X, Y or Z, was copper. metal explanation  © UCLES 2010 0653/21/O/N/10
5 (ii) Suggest two ways, other than using a catalyst, in which the student could increase the rate of reaction between metal X and dilute hydrochloric acid. 1 For Examiner's Use
(c) Fig. 2.2 shows another experiment in which the student added zinc carbonate to dilute sulfuric acid. A gas was given off and, when the bubbling stopped, some solid zinc carbonate remained in the mixture.
zinc carbonate solid zinc carbonate remaining
dilute sulfuric acid
Fig. 2.2 (i) State the chemical formula of sulfuric acid. ...