Centre ‘Candidate Number Number I Ty Candidate Name __ EXAMINATIONS COUNCIL OF ZAMBIA Examination for General Certificate of Education Ordinary Level Science 5124/3 Paper3 Practical Test Friday 44 JULY 2017 ‘Additional Materials: Electronic calculator (non programmable) and/or Mathematica tales Soft clean eraser Soft peno (ype B or HBs recommended) Groph paper Time 1 hour 30 minutes Instructions to Candidates Write your name, centre number and candidate number at the top of this page and on all separate answer paper used. ‘There are four questions in this question paper divided into sections A and B. ‘Answer all questions by writing your answers in the spaces provided in this question paper. Information for candidates ‘The number of marks is given in brackets [ ] at the end of each question or part question. Qualitative analysis notes are on page 9. ‘The Periodic Table is on page 10, Question | Examiners Cell phones are not allowed in the Examination room. | — 2 Section 3 4 Total eeczecenov7as ‘This question paper consists of 10 printed pagesPage 2 of 10 Section A (PHYSICS) [20 marks] Answer all questions in this section 1 _Inthis experiment you are required to determine the refractive index of water. as (eee ae ae Image of coin dy y | be sp -—Water Coin. fo meD Figure 1.4 (a) (Place a coin centrally inside the beaker as shown in figure 1.1. (ii) Pour some water into the beaker to approximately half full. (iii) Mark using a white board marker, the level of water. (iv) Using a ruler, measure and record this depth of water as D1. Dis .. cm (b) (i) View the coin from the top of the beaker and mark besides the beaker the apparent position of the coin. Using a ruler, measure the apparent depth and record it as di. .cm [1] Calculate the ratio Ds/dy. 2) (©) @ Add more water until the beaker Is almost full. Repeat steps (a) (iii) to (b) (iii) to obtain values of Dz and da then record them. De 1) & = tu Ratio Do/dy = (4 Scienoalst24a2017Page 3 of 10 (a) _ Determine the average of the two ratios. Average ratio = (21 (e) Mention one possible source of error in this experiment. QO) [Total: 10 marks] Selencel6124/32017 [Turn overPage 4 of 10 2 In this experiment, you will investigate the effect of length of conductor on the resistance of the conductor. You are provided with 5 different lengths of nichrome wire measuring 5 cm, 10 cm, 15 cm, 20 cm, and 25 cm. The following incomplete circuit has been set up for you. . (a) @_ Connect the 5 cm long nichrome wire between terminals A and B. Record the current reading on the ammeter in the table below. Repeat the procedure using the 10 cm, 15 cm, 20 cm and 25 cm long pieces of nichrome wire. Record each current reading against the length of the nichrome wire. Length of wirefom |5 | 40 | 15 | 20 |25 | current/A (2) (il) What happens to the resistance of the nichrome wire as length increases? Justify your answer. 2] (b) Plot a graph of current against length of conductor. 4] (©) With the aid of the plotted graph, work out the resistance of nichrome wire of length 18 cm. 2] [Total: 10 marks] Selenee!5124/90017Page 5 of 10 Section B (CHEMISTRY) [20 marks] Answer all questions in this section 3 ‘One of the factors that affect the rate of a chemical reaction is the concentration of the reactants. In this experiment, you will investigate the effect of diluting a reacting solution on the rate of a reaction. You will use the reaction of magnesium ribbons of the same mass with dilute hydrochloric acid labelled as solution Y. NB: Y is 2.0 M HCl. The reaction of HCI and Mg is; Maja) + 2HClaq) —> MgClaraqy + Hara) ‘The time taken for effervescence to stop suggests the rate of the reaction. You are provided with 3 empty beakers labelled A, B, C and solution Y, (a) (Measure 50 cm’, using a measuring cylinder, of solution ¥ and transfer the whole 50 cm? into beaker A. Add 50 cm? of distilled water to beaker B, Measure and add 50 cm’ of solution Y to beaker B. (iii) Add 150 cm? of distilled water to beaker €. Measure and add 50 cm’ of solution Y to beaker C. Calculate and record the new concentrations of HCI in beakers B and C and record your values in Table 3 (Show your working in the space below). seeeaisi242047 [Turn overPage 6 of 10 (b) (©) (Put one of the ribbons in beaker A and immediately start your stop watch and determine the reaction time until there is no more of the ribbon. Record the reaction time t; in minutes, taken for the whole ribbon to react, in Table 3. (ii) Put the second ribbon in beaker B and also record the time, in minutes taken for the ribbon to react completely as tz in table 3. (iii) Place the third and last ribbon in beaker € and record the time taken for the ribbon to react completely as ts in table 3. Table 3 Beaker | HCI concentration/mol/dm? _| Reaction time/minutes A 2.0 (@) On the grid provided, plot a graph for the three concentrations against ty,tz and ts. [4] i) Draw a best fit straight line through the 3 points. Selencelst2482017Page 7 of 10 Conclusion 1 What is the effect of diluting (reducing concentration) a reacting solution on the rate of the reaction? (1) 2 Which quantity of HCI was not changing i.e constant, in beakers A, B and €2 G1 [Total: 10 marks] ‘Scienoe/6124/312017 [Turn overPage 8 of 10 4 You are provided with solution Z which is a mixture of two salts. Both salts contain the same cations. All the ions are specified in the 5124/3 syllabus. Carry out the following test on Z and record the observations in the table below. Test and identify any gas evolved. TEST OBSERVATIONS | To a small portion of Zadd an equal | volume of acidified silver nitrate ra solution. solution. i (a) To @ small portion of Z, add sodi . | hydroxide solution drop by drop until a change is seen, | [1 To another small portion of 2, add an equal volume of acidified barium nitrate (b) To the same portion, add an cxeess | of sodium hydroxide solution. | 1 4 (a) To a small portion of Z, add | ammonium hydroxide solution drop | by drop until a change is seen. 7 | (b) To the same portion, add excess. | ‘ammonium hydroxide solution. 7 Conclusion 1 State the formulae of (a) Cation inz ) (b) Anions in Z @ uy 1 2 Wrile duwn the chemical formula for one of the salts in Z. Seleneals124/972017Page 9 of 10 NOTES FOR USE IN QUALITATIVE ANALYSIS Test for anions anion test test result carbonate (CO;*") | add dilute acid effervescence, carbon dioxide a ee chloride (Cr) acidify with dilute nitric acid, then | white ppt. [in solution] add aqueous silver nitrate lodide (I) acidlify with dilute nitric acid, then | yellow ppt. {in solution} ‘add aqueous lead (It) nitrate nitrate (NOS) add aqueous socium hydroxide then | ammonia produced 2 aluminium foil; warm carefully {in solution) | | sulphate (SO*) acidify with dilute nitric acid, then white ppt. | [in solution] add aqueous barium nitrate Test for aqueous cations (in solutions) cation effect of aqueous sodium effect of aqueous ammonia hydroxide ‘aluminium (AI) | white ppt,, soluble in excess white pot, insoluble in excess giving @ colourless solution ammonium (yxy) ammonia produced on warming calcium (Ca**) white ppt,, insoluble in excess | no ppt. or very slight white ppt copper(II) (Cu?*) | tight blue ppt., insoluble in light blue ppt,, soluble in excess excess giving a dark blue solution | iron(II) (Fe**) | green ppt., insoluble in excess green ppt., insoluble in excess “iron(II (Fe) | red-brown ppt, Insoluble in red-brown ppt, insoluble in excess | excess } zine (Zn**) | white ppt., soluble in excess white ppt., soluble in excess giving a | | giving a colourless solution colourless solution Test for gases gas —__| test and test result : : ammonia (NH) | turns damp red litmus paper blue carbon dioxide (CO>) | tums limewater mitky chlorine (Cl) | bleaches damp litmus paper hydrogen (Hz) | “pops” with a lighted splint ‘oxygen (02) [relights a glowing splint ‘sulphur dioxide (SO,) T turns aqueous potassium dichromate(VI) green Scenes 12432017 [Turn over‘200896 = 4} ‘JOWy/,,01 « 0'9=*N “(d72) eansseud pue eunjesediue) woos ye ,lup #Z $1 Se6 Aue Jo BJ9Ws UO Jo BLUNIOA ey "| as] __ fz S| al ia a ee) ee] ell |e] tly | oo I] “on | pw | “at |S" |S" | “fe” | tig | “ary” | “ng | aN" | wee | eam | saa 2 z neon eae tae cee cece Poa ee | amet oe ™m | oa | ou on | ka | ar | "po | na | ws | “4 | pn ad 20, s9u28 prouney €01-08+ oe ew ee eee, oo oe See im . 7 = on saryanng™ rs fo wi 1 dnoip ~ ‘Squauiayy o1p Jo Sei Dipoued SUL 41a3Hs Viva OF Jo OF ebed“@)- DOWNLOAD ECZ PAST PAPERS FROM YOUR PHONE OR PC www.zedpastpapers.com