SKEMA MRSM0 https://cikguadura.wordpress.com/ No Mark Scheme Sub Total mark (a) Number of protons in the nucleus of an atom (b) (i) P : 6 (c) 4 Q 6 (ii) R: (d) (i), 8, //. 8. (ii) / two (e) (i) P, Q (ii) Both atoms have same number of protons but different number of neutrons //same proton number but different nucleon number (iii) To estimate the age of fossils / artefacts TOTAL 9
No Mark Scheme Sub mark (a) (i) X Total (b) (ii) Y / Z (i) V (ii) Z (c) (i) Hydrochloric acid // nitric acid (a: formula) (ii) Reacts with alkali/base to form salt and water // reacts with reactive metal to form salt and hydrogen // reacts with metal carbonate to form salt, carbon dioxide and water // (d) (i) Sodium hydroxide/ NaOH //potassium hydroxide / KOH (name or chemical formula) (ii) Concentration = 0.00 x 0. 00 = 0.0 mol dm - TOTAL 9 4
No Mark Scheme Sub mark (a) (i) Pb +, Br - (both correct) a: name Total (ii) Na +, H +, SO4 -, OH - (all correct) a: name (b) (i) Lead r: formula (ii) Pb + + e Pb. correct formula. balanced equation (iii) Brown fumes / gas is released (c) (i) Hydroxide / OH - ion (ii) Anode: oxygen / O Cathode: hydrogen / H (iii) Sodium nitrate/potassium sulphate /sulphuric acid (If chloride solution is given, concentration must be 0.0 moldm - ) (a: any correct electrolyte) TOTAL 0 5
No Mark Scheme Sub Total mark 4 (a) A reaction in which oxidation and reduction occur simultaneously // at the same time (b) Show arrow pointing from B to A (c) x + (-)4 = - x = + 7 (r: 7) (d) Reduction (e) (i) FeSO4 (ii) Green to brown (iii) Fe + Fe + + e (iv) Add a few drops sodium hydroxide solution // ammonia solution until in excess Or Or Brown precipitate is formed Add a few drops of potassium thiocyanate solution Blood red colouration formed Add a few drops of potassium hexacyanoferate(ii) solution Dark blue precipitate formed TOTAL 0 6
No Mark Scheme Sub Total mark 5 (a) CaCO + HCl CaCl + CO + HO. Correct formulae. Balanced (b) Axis (label & unit) All points transferred correctly Curve smooth curve, correct shape (c) Correct tangent drawn at t = 60 s Calculation, answer and unit (0. ± 0.05) cm s - (d) Curve is below and becomes flat at time more than 80s Large marble chips (e) Small calcium carbonate chips has a larger total surface area than large calcium carbonate chips Frequency of effective collision between H + ions and calcium carbonate is higher Rate of reaction is higher TOTAL 7
No Mark Scheme https://cikguadura.wordpress.com/ Sub mark 6 (a) (i) Alcohol Total (ii) Any one structure (b). Label : heat, glass wool + compound J, compound K, porcelain chips and water. Arrangement of apparatus is functional Glass wool + compound J Porcelain chips Compound K Heat Water (c) (C H 5) n = 58 9n = 58 n = (C H 5) x Molecular formula = C 4H 0 (d) [Action] Add// Flow gas// Bubble compound K and L separately [Reagent] Acidified Potassium manganate (VII) solution// bromine water [in two different test tubes] [Observation] Purple solution of acidified Potassium manganate (VII) solution// Compound K decolourises brown bromine water but L does not (e) Acidified potassium manganate(vii) solution // Acidified potassium dichromate(vi) solution TOTAL 8
No Mark Scheme Sub mark Total 7(a) (i). Number of proton is. Number of neutron is. Number of electron is 4. Electron arrangement of X.8.// valence electron is 5. Electron around the nucleus 6. Proton and neutron located in nucleus 6 7. shells filled with electrons Any 6 (a)(ii). Atom X has valence electron. Group. Atom X have shell occupied with electrons [a.d.p atom] 4. Period 4 (b). Electron arrangement P;.8.8., Q;.6 and R;.4. To reach an octet electron arrangement. Atom P donate electron to form P + ions [infer from equation] 4. Atom Q accepts electron to form Q - ions [infer from equation] 5. Electrostatic attraction between P + ions and Q - ions forms ionic bond 6. Correct number of electrons 7. Label and nucleus shown 8. Each atom R provides 4 electron while each atom Q provide electron 9. atoms of Q share electrons with atom of W forming covalent compound, RQ 0. Correct number of electrons. Label and nucleus shown Max: 0 TOTAL 0 9
No Mark Scheme Sub mark 8 (a) Any 4 correct comparison Glass Ceramic Hard and brittle Hard and brittle Chemically inert Chemically inert Withstand compression Withstand compression Good heat/ electrical insulator Good heat/ electrical insulator Impermeable // non porous Porous Transparent Opaque Can be reheated/ recycled Cannot be reheated/ remelted / recycled Total 4 (b) Medicine Ubatan Type Function A Analgesic To lessen / relieve pain B Antibiotic Kill// retards growth of bacteria 4 C Antidepressant 5 To reduce tension, anxiety and fear 6 6 (c) (i) (c) (ii). Soap causes formation of solid/ scum in hard water. No solid/scum formed in mixture of detergent in hard water. Detergent is better 4. [Explanation] Experiment II: less concentration of soap ions present // requires more soap // detergent forms soluble salt in hard water.. Detergent particles/molecule/anion consist of hydrophobic/ hydrocarbon/ covalent and hydrophilic/ ionic part. Hydrophilic part dissolves in water. reduces surface tension of water 4. Hydrophobic part dissolves in oil 5. When[scrubbing], water molecules attract the hydrophilic part, thus pulling the oily stain 6. Soap emulsifies oil/ breaks oil into small droplet 4 6 TOTAL 0 0
No Mark Scheme Sub mark 9 (a)(i). Lead(II) sulphate / PbSO4 is solid / insoluble salt Total (a) (ii) (b). Cannot separate lead(ii) sulphate from excess lead(ii) oxide// incomplete reaction between lead(ii) oxide and sulphuric acid Step I. Add lead(ii) oxide, PbO powder to nitric acid solution.. Stir and warm the mixture, filter the mixture. Filtrate is colourless. Step 4. Add sulphuric acid / sodium sulphate [any soluble sulphate solution] to lead nitrate solution/ filtrate 5. White precipitate formed 6. Filter the mixture, dry by pressing between filter papers Chemical Equation 7. Step I: PbO + HNO Pb(NO) + HO 8. Step II: Pb(NO) + HSO4 PbSO4 + HNO. Add nitric acid to lead(ii) carbonate. Pass gas through lime water. Lime water turns cloudy/ chalky/ milky 4. Pour solution produced into test tubes Test tube 5. Add aqueous sodium hydroxide until excess, shake. 6. If white precipitate formed and dissolves in excess NaOH, Zn + or Al + or Pb + ions present Test tube 7. Add aqueous ammonia, NH until in excess shake. 8. If white precipitate formed and insoluble in excess NH, Al + or Pb + ions present, 8
Test tube 9. Add sulphuric acid, HSO4 shake. 0. White precipitate formed 0 Case : TOTAL 0 If sulphuric acid is used in P, Award M,, 4, 5, 7, 9 No Mark Scheme Sub mark Total 0 (a). No of mole CuSO4 = 50 = 0.05 mol 000. Heat released = 0.05 0000 = 0500 J / 0.5 kj. Heat released = mcѳ 0500 = 50 x 4. x Ѳ 4. Ѳ = 50 o C 4 (b) (i). To break the bonds between H H and Cl Cl, heat energy is absorbed. // Energy absorbed during breaking of bonds. When bonds are formed between H Cl, heat energy is released. // Energy released during formation of bonds. The energy absorbed to break H H and Cl Cl bonds, 679 kj mol - is less than energy released to form H- Cl bonds, 864 kj mol - (ii) 4. So the reaction is exothermic. Energy Diagram. Axis : Energy labeled, upwards arrow energy level of the products < the energy level of the reactants 4. Correct reactants and products of reaction, H with its value
(c). Measure [5.0 50.0] cm of copper(ii) sulphate [0.-.0] mol dm - solution. Pour the solution into a plastic/ polystyrene cup. Record the initial temperature of the solution 4. Add excess/ spatula of zinc powder into copper (II) sulphate solution 5. Stir the mixture 6. Record the highest temperature reached 7. Data - Initial temperature of copper (II) sulphate solution = T - Highest temperature = T 8. Heat given out = 5 x 4. (T T) = X J 9. Mole of copper(ii) sulphate = MV 000 = Y 0. H = - X/Y = - Z kjmol - 0 TOTAL 0 END OF MARKING SCHEME
(a) KK050 Observing SKEMA MRSM0 https://cikguadura.wordpress.com/ Able to state correct observations for all sets of experiments Set Observation I A few blue spots are formed II A lot of blue spots are formed III No blue spot Able to state correct observations for sets of experiments Able to state correct observation for set of experiment / Able to give idea on observation 0 No response given OR wrong response (b)(i) KK0504 Making Inferences Able to state correct inferences for all sets of experiments. For Set I and Set II, must have comparison Set Inference I A small amount of Fe + ions is formed // Lower concentration of Fe + ions // A small amount of iron corrodes/rust II A large amount of Fe + ions is formed // Higher concentration of Fe + ions is formed// A large amount of iron corrodes/rust III No Fe + ions is formed // Iron does not rust/corrodes Able to state correct inferences for sets of experiments. Able to state correct inference for set of experiment 0 No response given OR wrong response
(b)(ii) KK0506 Communicating Able to arrange all three metals in ascending order of electropositivity. Copper, Iron, Magnesium. Cu, Fe, Mg Able to arrange two adjacent metals in ascending order of electropositivity. Magnesium, Copper, Iron / Mg, Cu, Fe. Copper, Iron, Magnesium / Cu, Fe, Mg Able to place either Cu or Mg in the right place Cu, Mg, Fe / Fe, Cu, Mg 0 No response given OR wrong response (c) KK050 Controlling variables Able to state all THREE variables correctly : Manipulated variable: Metal coiled to / in contact with iron nail Responding variable: Constant variable: Formation of blue spots // Rusting/corrosion of iron Gel / potassium hexacyanoferate(iii) // Temperature // Iron nail Able to state any TWO variables correctly Able to state ONE variable correctly 0 No response given OR wrong response 4
(d) KK05 Making Hypothesis Able to state the relationship correctly between the manipulated variable and the responding variable with direction. * MV RV :. When iron is coiled [in contact] with magnesium/ a more electropositive metal, no blue spot is formed / iron does not rust.. When iron is coiled [in contact] with copper/ a less electropositive metal, more blue spots are formed / more iron will rust. Able to state the relationship between the manipulated variable(mv) and responding variable (RV)* // * RV MV :. No blue spot is formed / iron does not rust when iron is coiled [in contact] with a more electropositive metal.. When iron is coiled [in contact] with a more reactive metal, no blue spot is formed / iron does not rust. Able to give idea regarding hypothesis. :. When iron is coiled [in contact] with a metal, blue spots are formed.. Iron without any contact with any metal will rust// forms blue spots. 0 No response given OR wrong response (e) KK0505 Predicting Able to predict the observation correctly More blue spots are formed than in Set II Able to predict the observation less accurately A lot of blue spots are formed. Able to give idea on the prediction. Blue spots are formed. 0 No response given OR wrong response 5
(f) KK0509 Defining operationally Able to state the operational definition for the rusting of iron correctly. :. More/ a lot of blue spots are formed when iron is coiled [in contact] with a less electropositive metal in a gel containing potassium hexacyanoferate(iii).. No blue spot is formed when iron is coiled [in contact] with a more electropositive metal in a gel containing potassium hexacyanoferate(iii). Able to state the operational definition for the rusting of iron less accurately.. A lot of blue spots are formed when iron is coiled [in contact] with a less electropositive metal.. No blue spots is formed when iron is coiled [in contact] with a more electropositive metal. Able to state an idea of the operational definition Blue spots are formed when iron rust. 0 No response or wrong response (a) KK050 Measuring and using numbers Able to record the four ammeter readings correctly to one decimal place with unit. s: Substance Sodium chloride solution Ethanol Glucose Lead(II) nitrate solution Ammeter reading.6 A 0.0 A 0.0 A.6 A Able to record the four ammeter readings correctly with unit, without decimal place // Able to record the four ammeter readings correctly with decimal place, without unit // Able to record the three ammeter readings correctly to one decimal place with unit. Able to record at least two ammeter readings correctly. 0 No response given OR wrong response 6
(b) KK050 Classifying Able to classify all the substances correctly into electrolytes and non - electrolytes Electrolyte Sodium chloride solution Lead(II) nitrate solution a: correct formula of substances Able to classify at least two substances correctly Non-electrolyte Ethanol Glucose Electrolyte Sodium chloride solution Lead(II) nitrate solution Ethanol Non-electrolyte Glucose OR Able to group all the substances correctly but wrongly classified. Electrolyte Ethanol Glucose Able to classify at least one substance correctly. 0 No response or wrong response Non-electrolyte Sodium chloride solution Lead(II) nitrate solution 7
(c)(i) KK0507 Using space and time relationship Able to state the expected ammeter reading accurately The ammeter reading decreases // The ammeter reading is less than.6 A Able to state the expected ammeter reading inaccurately [value given without unit] The ammeter reading is less than.6 ( 0.0 < x <.6 ) Able to give an idea for the ammeter reading Ammeter reading changes // less deflection 0 No response or wrong response (c)(ii)kk0508 Interpreting data Able to give explanation correctly by stating all three information. H + ions and Cl - ions discharged. Concentration/ number of free moving ions decreases.. Electrical conductivity decreases / Amount of current flow decreases Able to give explanation by stating at least two information Able to give explanation by stating at least one information / any idea relating to the explanation 0 No response given OR wrong response 8
(a) KK050 Problem Statement Able to state suitable aim of experiment correctly : To construct the Electrochemical Series for copper, iron, magnesium and zinc using a voltaic cell Able to state aim of experiment less accurately To construct the Electrochemical Series for copper, iron, magnesium and zinc // To construct the Electrochemical Series using a voltaic cell Able to give an idea about aim of experiment Suggested Answer To construct the Electrochemical Series 0 No response or wrong response (b) KK050 List of Variables Able to state all the three variables correctly Manipulated variable : Pair of metals // List at least pairs Mg / Cu, Zn / Cu, Fe / Cu Responding variable : Potential difference / Voltage / Voltmeter reading Controlled variable : Electrolyte used / [the name of a suitable electrolyte] Able to state any two of the variables correctly // Able to state three variables inaccurately Able to state one variable correctly 0 No response or wrong response 9
(c) KK050 Statement of hypothesis Able to state the relationship correctly between the manipulated variable and the responding variable with direction. * MV RV :. The further the distance between two metals in Electrochemical Series, the larger the difference in potential difference of a voltaic cell / voltage / the voltmeter reading.. As the distance between two metals in Electrochemical Series increases, the voltage / potential difference of a voltaic cell / voltmeter reading increases. Able to state the relationship between the manipulated variable (MV) and responding variable (RV)* less accurately * RV MV Able to give idea regarding hypothesis : The metals influence the voltage / potential difference of a voltaic cell / voltmeter reading. 0 No response given OR wrong response (d) KK0505 List of substances and apparatus Able to list complete substances and apparatus. [can be infer from a diagram(all apparatus labeled) or from procedure] Suggested Answer: Substances: Iron, magnesium, zinc, copper, [a named electrolyte], sand paper Apparatus: Beaker, voltmeter, connecting wires Able to list basic substances and apparatus. Suggested Answer Substances: Iron, magnesium, zinc, copper, [a named electrolyte] Apparatus: [any suitable container], voltmeter Able to give an idea of the substances and apparatus. Suggested Answer Substances: Any metal, any electrolyte Apparatus : Voltmeter 0 No response or wrong response 0
(e) KK0504 Stating the Procedure Able to state all steps in the procedure correctly Suggested Answer. Clean the magnesium strip and copper strip with sandpaper.. Immerse the two strips into dilute sulphuric acid (any suitable electrolyte). Connect the two strips to a voltmeter. 4. Record the potential difference/ voltage of the two metals. 5. Repeat all steps by replacing magnesium strip with zinc strip and iron strip. Able to state steps *,, 4 and 5 correctly * (can use dip ) Able to state steps * and correctly * (can use dip ) 0 No response or wrong response https://cikguadura.wordpress.com/ (f) KK050 Tabulation of data Able to present a table to record the following items correctly. Pair of metals ( at least pairs Mg / Cu, Zn / Cu, Fe / Cu). Potential difference (V) Suggested Answer: Pair of metals Mg / Cu Zn / Cu Fe / Cu Potential difference (V) Able to give an idea on tabulation of data, at least one information stated in the table Suggested Answer: Pair of metals 0 No response or wrong response END OF MARKING SCHEME