85 q.5 a. an oxidizing agent. 85 q.14 a. nh cl b. no c. hno d. n …€¦ · 03-05-2009 ·...

Redox and electrolysis / Section 3 / Sect3pp.doc / S. W. Tse / P.1

85 Q.5 The element with an atomic number of 19 is likely to be A. an oxidizing agent. B. a reducing agent. C. a non-metal. D. chemically unreactive. 85 Q.14 In which of the following substances does nitrogen have the lowest oxidation number? A. NH4Cl B. NO2 C. HNO2 D. N2 85 Q.15 MnO4

-(aq) + 8H + + xe - → Mn 2+(aq) + 4H2O(l) Which of the following statements about the above equation is correct? A. The value of x is 6. B. 1 mole of MnO4

-(aq) produces 2 moles of Mn 2+(aq). C. The change in oxidation number of Mn is from -1 to +2. D. It represents a reduction reaction. 85 Q.40 A fork which is made of metal M can be silver-plated by the set-up shown below: When a current has been passed through the solution for same time, which of the following will occur?

(1) Silver ions will migrate to the silver electrode. (2) Silver ions will be reduced at the cathode. (3) The metal M will go into solution as ions. (4) The mass of the fork will increase.

A. (1) and (3) only B. (1) and (4) only C. (2) and (3) only D. (2) and (4) only

metal Msilver electrode

silver nitrate solution


85 Q.41 In which of the following equations is the substance underlined acting as an oxidizing agent?

(1) H2SO4 + BaCl2 → BaSO4 + 2HCl (2) Cu + 2AgNO3 → 2Ag + Cu(NO3)2 (3) SO2 + I2 + 2H2O → 2HI + H2SO4 (4) SO2 + 2H2S → S + 2H2O

A. (4) only B. (1) and (2) only C. (3) and (4) only D. (1), (2) and (3) only Directions: Question 85 Q.53 and 85 Q.54 refer to the following diagrams. 85 Q.53 Which of the following metals, when used as electrode X, would produce the largest reading on the voltmeter? A. iron B. lead C. magnesium D. zinc 85. Q.54 If electrode X is zinc, which of the following statements concerning the cell is INCORRECT? A. Electrons flow from electrode X to the copper electrode in the external circuit. B. Chlorine is given off at electrode X. C. Hydrogen is given off at the copper electrode. D. The mass of electrode X gradually decreases. 86 Q.1 The atomic structure of an element is:

Number of electrons 17 Number of protons 17 Number of neutrons 19

In its compounds, this element is most likely to have an oxidation number of A. +2 B. +1 C. -1 D. -2

electrode X copper

potassium chloride solution

V


86. Q.6 aCl2 + 6OH - → bCl - + ClO3

- + 3H2O When the above equation is balanced, the values for a and b should be: a b A. 1 1 B. 2 3 C. 3 5 D. 4 7 86 Q.12 heat (NH4)2Cr2O7 → N2 + 4H2O + Cr2O3 When ammonium dichromate is decomposed according to the above equation, which of the following correctly describes the changes in oxidation numbers of nitrogen and chromium? Oxidation number of nitrogen Oxidation number of chromium A. Increases increases B. Increases decreases C. Decreases increases D. Decreases decreases 86 Q.13 In the following reaction: 2I - + H2O2 + 2H + → I2 + H2O A. I - is reduced and H + is oxidized. B. I - is reduced and H2O2 is oxidized. C. I - is oxidized and H2O2 is reduced. D. I - is oxidized and H + is reduced. 86 Q.14 If 0.1M aqueous solutions of the following compounds were electrolyzed using graphite electrodes, which one would give hydrogen at the cathode and oxygen at the anode? A. copper(II) sulphate B. sodium hydroxide C. potassium iodide D. silver nitrate 86 Q.17 In which of the following reactions is sulphur dioxide acting as an oxidizing agent? A. 3SO2 + Cr2O7

2- + 2H + → 3SO42- + 2Cr 3+ + H2O

B. SO2 + 2H2S → 3S + 2H2O C. SO2 + PbO2 → PbSO4 D. 2SO2 + O2 → 2SO3


86 Q.20 In which of the following compounds does nitrogen have the lowest oxidation number? A. HNO2 B. KNO3 C. NO D. NH3 86 Q.33 Both molten lead(II) bromide and iron can conduct electricity.

They are both electrolytes.

1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 86 Q.39 When aqueous copper(II) sulphate is electrolyzed using copper electrodes, the equation(s) for the reaction(s) which occur(s) at the anode is/are: (1) Cu(s) → Cu2+(aq) + 2e (2) Cu2+(aq) + 2e → Cu(s) (3) SO4

2-(aq) → SO2 + O2 + 2e A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 86 Q.42 Which of the following metal oxides can be reduced by the method illustrated in the above diagram? (1) Fe2O3 (2) MgO (3) PbO A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only

metal oxide

town gas

heat


87 Q.10 During electrolysis, electricity passes through the electrolyte as a result of the movement of A. cations only. B. anions only. C. cations and anions. D. mobiles electrons. 87 Q.11 Referring to the above diagram, the largest current flowing from iron to metal X in the external circuit can be obtained when X is A. copper. B. magnesium. C. silver. D. zinc. 87 Q.12 Tin plating can be used to prevent iron cans from rusting because A. tin is higher than iron in the electrochemical series. B. the tin protects the iron from exposure to air. C. tin corrodes more readily than iron. D. the tin and the iron readily form an alloy which does not corrode. 87 Q.14 Referring to the above diagram, which of the following changes would occur when a current is passed through the solution for some time? A. Sodium is formed at X and sulphur dioxide is liberated at Y. B. Oxygen is liberated at X and hydrogen is liberated at Y. C. The colour of the solution around X and Y fades. D. The colour of the solution becomes blue around X and red around Y.

iron metal X

postaaium chloride solution

A current

platium electrode X

platinum electrode Y

saturated sodium sulphate solution containing litmus


87 Q.39 In industry, graphite electrodes are always used in the electrolysis of concentrated sodium chloride solution because graphite (1) is cheap. (2) conducts electricity. (3) is chemically inert. (4) is a reducing agent. A. (1) and (3) only B. (2) and (4) only C. (1), (2) and (3) only D. (2), (3) and (4) only 87 Q.42 Which of the following are redox reaction? (1) Mg(s) + CuSO4(aq) → MgSO4(aq) + Cu(s) (2) Al(OH)3(s) + NaOH(aq) → NaAlO2(aq) + 2H2O(l) (3) MnO2(s) + 4HCl(aq) → MnCl2(aq) + Cl2(g) + 2H2O(l) A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 87 Q.43 Which of the following statements is / are true for chlorine, bromine and iodine? (1) They exist as diatomic molecules at room temperature and pressure. (2) Their oxidizing power decreases as their relative molecular masses increase. (3) Their colours darken as their relative molecular masses increase. A. (1) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) only 88 Q.1 Which of the following statements concerning the Periodic Table is correct? A. In any group, the atomic size of the elements decreases with increasing atomic number. B. In any period, the metallic character of the elements increases with increasing atomic

number. C. Group I elements are oxidizing agents and Group VII elements are reducing agents. D. The compounds formed between Group IV elements and other elements are mostly covalent. 88 Q.32 Potassium iodide solution turns brown on adding chlorine water.

The iodide ions are reduced by chlorine to give iodine.

1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False -----


88 Q.38 Which of the following metal oxides can be reduced by carbon? (1) magnesium oxide (2) iron(III) oxide (3) copper(II) oxide A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 89 Q.10 A solution of silver nitrate was electrolyzed under a steady current, using silver electrodes. Which of the following graphs correctly represents the change in mass of the anode with time? A.

B.

C.

D.

89 Q.12 When a solution of magnesium sulphate of known concentration is electrolyzed using platinum electrodes, which of the following is a correct description of what happens? Number of moles of Mg2+(aq) Number of moles of SO4

2-(aq) pH value of the solution A. decreases decreases increases B. remains unchanged decreases decreases C. decreases remains unchanged remains unchanged D. remains unchanged remains unchanged remains unchanged 89 Q.13 The anode of a dry cell is usually made of A. zinc. B. iron. C. tin. D. lead.

Mass

Time

Mass

Time

Mass

Time

Mass

Time


89 Q.14 In which of the following reactions is the underlined substance reduced? A. Cu(OH)2(s) + 4NH3(aq) → [Cu(NH3)4](OH)2(aq) B. 2H+(aq) + CO3

2-(aq) → CO2(g) + H2O(l) C. Cl2(g) + 2Fe2+(aq) → 2Fe3+(aq) + 2Cl-(aq) D. 2Ag+(aq) + Zn(s) → 2Ag(s) + Zn2+(aq) 89 Q.29 During electrolysis, reduction occurs at the cathode.

Cations gain electrons at the cathode.

1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 89 Q.30 Magnesium is a stronger oxidizing agent than sodium.

Mg2+ accepts electrons more readily than Na+(aq).

1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 89 Q.38 K2Cr2O7(aq) + 3K2SO3(aq) + 4H2SO4(aq) → Cr2(SO4)3(aq) + 4K2SO4(aq) + 4H2O(l) In the above equation, which of the following oxidation number is / are changed? (1) Cr (2) S (3) O A. (1) only B. (1) and (2) only C. (2) and (3) only D. (1), (2) and (3) 90 Q.1 Which of the following elements in the third period of the Periodic Table is the strongest reducing agent? A. sodium B. sulphur C. chlorine D. aluminium


90 Q.5 In going down the group VI elements of the Periodic Table, there is an increase in (1) the size of the atoms. (2) the melting point of the elements. (3) the oxidizing power of the elements. Which of the following combinations is correct? A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 90 Q.19 In which of the following pairs of substances is the oxidation number of the sulphur atom and the nitrogen atom the same A. H2SO4 and HNO3 B. SO2 and HNO2 C. SCl2 and NO D. NaHSO4 and NH3 90 Q.23 A student tries to plate a copper ring with nickel using the set-up below: Which of the following combinations is correct?

Anode cathode Electrolyte A. Copper ring nickel rod Ni2+(aq) B. Nickel rod copper ring Ni2+(aq) C. Copper ring nickel rod Cu2+(aq) D. Nickel rod copper ring Cu2+(aq) 90 Q.24 Which of the following pairs of metals would be expected to give the largest voltage when they are used as electrodes in a simple chemical cell using potassium nitrate solution as the electrolyte? A. Zn and Pb B. Mg and Ag C. Pb and Cu D. Fe and Mg

copper ring

d.c. power supply

electrolyte

nickel rod


Directions: Questions 91 Q.6 and 91 Q.7 refer to the following electrolysis experiment. 91 Q.6 The gases collected at electrodes X and Y respectively are in the volume ratio of A. 1:1 B. 1:2 C. 1:4 D. 2:1 91 Q.7 Which of the following statements concerning the experiment is / are correct?

(1) The pH value of the potassium sulphate solution remains unchanged at the end of the experiment.

(2) The concentration of the potassium sulphate solution remains unchanged at the end of the experiment.

(3) The products of electrolysis at electrodes X and Y would remain unchanged if 2M sulphuric acid were used instead of 2M potassium sulphate solution.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 91 Q.9 Which of the following combinations would produce the largest current flowing metal X to metal Y in the external circuit? metal X metal Y A. Fe Cu B. Mg Ag C. Ag Zn D. Cu Pb

electrode X electrode Y

2M potassium sulphate solution

Acurrent

wire

filter paper soaked with sodium chloride solution

metal X

metal Y


91 Q.14 Sulphur dioxide is passed into a test-tube containing potassium dichromate solution acidified with dilute sulphuric acid. The colour of the solution gradually changes from orange to green. Which of the following statements concerning the above experiment is correct? A. Sulphur dioxide is oxidized to sulphate. B. The green colour is due to the presence of Cr2+(aq) ions. C. The dilute sulphuric acid acts as a catalyst. D. The oxidation number of chromium changes from +7 to +2 in the reaction. 91 Q.43 Cl2(aq) + 2I-(aq) → I2(aq) + 2Cl-(aq) Which of the following statements concerning the above reaction are correct? (1) I-(aq) acts as a reducing agent. (2) Chlorine is a stronger oxidizing agent than iodine. (3) The reaction is a displacement reaction. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 92 Q.4 Consider the following table:

Element W X Y Z Atomic Number 9 10 14 19

Which of the following elements is likely to be oxidizing agent? A. W B. X C. Y D. Z


Directions: Question 92 Q.9 and 92 Q.10 refer to the following diagrams: 92 Q.9 Which of the following represents the correct order of activity of the metals P, Q and R and S? A. R, P, Q, S B. Q, P, R, S C. P, Q, S, R D. P, R, S, Q 92 Q.10 Which of the two metals used as electrodes would give the largest cell voltage? A. Q and R B. Q and S C. S and R D. S and P 92 Q.12 Using 1 mole of reactant, which of the following chemical changes involves the highest number of electrons? A. CrO4

2-(aq) → Cr3+(aq) B. Cr2O7

2-(aq) → Cr3+(aq) C. MnO4

-(aq) → Mn2+(aq) D. MnO4

2-(aq) → MnO2(s)

sodium chloride solution

metal Q metal P

cell voltage = +1.1 V

V


metal R metal P

cell voltage = -1.1 V

V


metal S metal P

cell voltage = +1.5 V

V


92 Q.37 Which of the following aqueous solutions, when electrolyzed using carbon electrodes, will liberate only gaseous products at both electrodes? (1) KOH(aq) (2) AgNO3(aq) (3) MgCl2(aq) A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 92 Q.46 Sulphur dioxide is an oxidizing agent. Sulphur dioxide can decolorize bromine

water. 1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 93 Q.15 The oxidation number of copper remains unchanged when A. magnesium ribbon is added to copper (II) sulphate solution. B. sodium carbonate solution is added to copper (II) nitrate solution. C. carbon is heated with copper (II) oxide. D. copper foil is burnt in chlorine. 93 Q.16 In which of the following equations does the underlined substance undergo reduction? A. 2H2O + 2K → 2KOH + H2 B. Fe2(SO4)3 + 2KI → 2FeSO4 + K2SO4 + I2 C. 2H2S + SO2 → 3S + 2H2O D. NaClO + SO2 + H2O → NaCl + H2SO4


93 Q.17 With reference to the above diagram, which of the following statements is correct? A. The electrode made of metal X is the positive pole. B. Copper is at a higher position in the electrochemical series than metal X. C. The mass of the copper electrode decreases. D. The mass of the electrode made of metal X decreases. 93 Q.19 In the above experiment, which of the following major products will be liberated at the electrodes? cathode anode A. magnesium oxygen B. magnesium bromine C. hydrogen bromine D. hydrogen oxygen 93 Q.24 There is gradual change in the properties of halogens from chlorine to iodine. Which of the following properties are in the order chlorine < bromine < iodine (1) oxidizing power (2) density (3) boiling point A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

current

copper electrode

electrode made of metal X

dilute sulphuric acid

A

carbon electrode

carbon electrode

concentrated magnesium bromide solution


94 Q.4 Both rubidium (Rb) and sodium are elements in Group I of the Periodic Table, but rubidium is more reactive than sodium. When a rubidium hydroxide solution is electrolyzed using platinum electrodes, hydrogen gas is liberated at the cathode. Which of the following statements is a correct explanation for the phenomenon described above? A. The H+(aq) ion accepts an electron more readily than the Rb+(aq) ion. B. The H+(aq) ion is more mobile than the Rb+(aq) ion and migrates faster to the cathode. C. Rubidium is first liberated, but it reacts immediately with water to give hydrogen gas. D. The concentration of H+(aq) ions is higher than that of Rb+(aq) ions in the rubidium

hydroxide solution. 94 Q.12 In which of the following experiments will a redox reaction occur? A. adding copper turnings to iron (II) nitrate solution B. adding bromine water to potassium chloride solution C. adding iron filings to silver nitrate solution D. adding sodium chloride solution to silver nitrate solution 94 Q.13 When a substance X is electrolyzed using platinum electrodes, a gas is collected at each electrode. X may be A. silver nitrate solution. B. potassium chloride solution. C. molten sodium chloride. D. molten copper (II) chloride 94 Q.17 In which of the following reactions does sulphur dioxide act as an oxidizing agent? A. SO2 + 2Mg → 2MgO + S B. SO2 + 2KOH → K2SO3 + H2O C. SO2 + Cl2 + 2H2O → H2SO4 + 2HCl D. 5SO2 + 2KMnO4 + 2H2O → K2SO4 + 2MnSO4 + 2H2SO4 94 Q.34 Which of the following reagents can be used to distinguish between sodium sulphite solution and sodium sulphate solution? (1) barium chloride solution (2) acidified potassium permanganate solution (3) potassium iodide solution A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only


95 Q.10 In which of the following equations does the underlined substances become reduced? A. CuSO4 + Zn → Zn SO4 + Cu B. 2FeCl2 + Cl2 → 2FeCl3 C. Pb(OH)2 + 2HNO3 → Pb(NO3)2 + 2H2O D. MgCO3 + 2HCl → MgCl2 + CO2 + H2O 95 Q.11 A student tries to electroplate an iron ring with nickel using the set-up shown below. Which of the following combinations is correct? Solution X Anode Cathode A. Iron (II) sulphate solution Iron ring Nickel rod B. Iron (II) sulphate solution Nickel rod Iron ring C. Nickel (II) sulphate solution Iron ring Nickel rod D. Nickel (II) sulphate solution Nickel rod Iron ring 95 Q.24 Consider the following equation. 2FeSO4.7H2O(x) → Fe2O3(y) + SO3(z) + SO2(g) + 14 H2O(l) Which of the following combinations is correct? x y z A. aq s g B. aq s l C. s aq s D. s s g

nickel rod iron ring

solution X

d.c. supply


95 Q.30 Which of the following statements is / are correct? (Refer to the following chemical equation) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) (1) Carbon monoxide is an oxidizing agent. (2) The oxidation number of carbon changes from +2 to +4. (3) The oxidation number of iron changes from +2 to 0. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 95 Q.32 Astatine is a Group VII element below iodine in the Periodic Table. Which of the following statements concerning astitine is / are correct? (1) It is a liquid at room temperature and pressure. (2) It reacts with sodium to form an ionic compound. (3) It is a stronger oxidizing agent than iodine. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 95 Q.33 Which of the following statements concerning a silver oxide cell is / are correct? (1) The cell is rechargeable. (2) The cell can maintain a steady voltage during discharge. (3) The positive electrode of the cell is silver oxide. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 95 Q.37 In the set-up shown metal X is more reactive than metal Y. Which of the following statements concerning this set-up is / are correct? (1) Electrolysis occurs inside the lemon. (2) Chemical energy is changed into electrical energy. (3) Electrons flow from metal Y to metal X in the external circuit. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

metal X metal Y

A

lemon


95 Q.40 Which of the following methods can produce hydrogen? (1) adding zinc to water (2) electrolyzing dilute sulphuric acid (3) adding magnesium to dilute hydrochloric acid A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 96 Q.7 Which of the following metals would produce the smallest voltage in the above set-up A. iron B. aluminium C. copper D. magnesium 96 Q.25 Which step in the above flow chart involves the largest change in oxidation number of nitrogen? A. step 1 B. step 2 C. step 3 D. step 4

metal silver

sodium nitrate solution

V

N2 NH3 NO NO2 HNO3

step 1 step 2 step 3 step 4


96 Q.27 Which of the following statements concerning the above set-up is correct? A. Electrons flow from the lead electrode to the magnesium electrode through the external

circuit. B. Electrons flow through the salt bridge. C. The mass of the lead electrode remains unchanged. D. Oxidation occurs at the magnesium electrode. Directions: 96 Q.30 and Q.31 refer to the following experiment. 96 Q.30 Which of the following combinations is correct? Gas X Gas Y A. chlorine hydrogen B. chlorine oxygen C. hydrogen chlorine D. oxygen hydrogen 96 Q.31 Which of the following statements concerning the above experiment is / are correct? (1) Platinum electrodes should be used. (2) The concentration of Na+(aq) ions around the cathode increases. (3) The solution changes from colourless to pink. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

lead electrode

1M magnesium nitrate solution

V magnesium electrode

1M lead (II) nitrates solution

salt bridge

electrode electrode

concentrated sodium chloride solution containing phenolphthalein

gas X gas Y


96 Q.35 In which of the following process will lead be produced? (1) the electrolysis of molten lead (II) bromide (2) heating lead (II) oxide strongly (3) adding magnesium to lead (II) nitrate solution A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 96 Q.42 X is element. It can form a cation X2+ which has an electronic arrangement 2,8,8. Which of the following statements concerning X are correct? (1) X is a strong oxidizing agent. (2) X is in Period 4 of the Periodic Table. (3) X burns in oxygen with a brick red flame. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 96 Q.46 Zinc-carbon dry cells are rechargeable. The electrolyte used in zinc-carbon dry cells

is potassium hydroxide. 1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 97 Q.4 Which of the following statements concerning the elements in the third period of the Periodic Table is correct? A. Both sulphur and chlorine can be reduced by aqueous sodium sulphite. B. Magnesium is a stronger reducing agent than sodium. C. Phosphorus and chlorine form a covalent compound. D. Magnesium burns in oxygen to form an acidic oxide. 97 Q.7 During the electrolysis of 1M copper (II) chloride solution using copper electrodes, which of the following changes would occur at the electrodes? Cathode Anode A. hydrogen liberated chlorine liberated B. copper deposited chlorine liberated C. copper dissolved copper deposited D. copper deposited copper dissolved


97 Q.8 Which of the following conversions involves the smallest change in oxidation number of the underlined element? A. C(s) → CO2(g) B. NO3

-(aq) → NO2(g) C. SO3

2-(aq) → SO42-(aq)

D. MnO4-(aq) → Mn2+(aq)

97 Q.11 A zinc-carbon cell is connected to a voltmeter as shown in the above diagram. Which of the following concerning the set-up is INCORRECT? A. Electrons flow from the zinc case to the carbon rod in the external circuit. B. The zinc case gradually becomes thinner as the cell discharges. C. Manganese (IV) oxide acts as an oxidizing agent. D. Ammonium chloride acts as a reducing agent. 98 Q.21 Consider the following experiment.

Which of the following statements concerning the above experiment is correct ? A. Permanganate ions migrate into the salt bridge. B. Electrons flow from electrode X to electrode Y in the external circuit. C. Carbon electrodes are used because they are chemically inert. D. The half equation for the change occurring at electrode Y is

Fe2+ + 2e → Fe

V

moist paste of ammonium chloride

zinc case manganese (IV) oxide and carbon powder

carbon rod


98 Q.22 In which of the following reactions does the underlined substance act as a reducing agent ? A. SO2 + 2H2S → 3S + 2H2O B. Pb(NO3)2 + H2SO4 → PbSO4 + 2HNO3 C. 2HCl + MgO → MgCl2 + H2O D. 2KBr + Cl2 → 2KCl + Br2 98 Q.27 Consider the following chemical equation : Zn + pMnO2

+ qNH4+ → Zn2+ + xMn2O3 + yNH3 + zH2O

Which of the following combinations is correct ? x y z A. 1 2 1 B. 1 3 2 C. 2 3 2 D. 2 2 3 99 Q.9 In which of the following reactions is the underlined reactant reduced? A. Cu2+ + 2OH- → Cu(OH)2 B. SO2 + 2Mg → 2MgO + S C. 2NH3 + 3CuO → 3Cu + N2 + 3H2O D. Zn + 2AgNO3 → Zn(NO3)2 + 2Ag 99 Q.12 Consider the electrolysis experiment shown below:

Which of the following statements concerning this experiment is correct ? A. The mass of the impure copper rod deceases. B. The blue colour of the copper(II) sulphate solution gradually fades off. C. Oxidation takes place at the pure copper rod. D. The electrolysis process can enhance the corrosion resistance of copper.


99 Q.21 Consider the following chemical equation:

2HNO3 + xFeSO4 + yH2SO4 → zFe2(SO4)3 + 4H2O + 2NO Which of the following combinations is correct ? x y z A. 2 1 1 B. 4 3 2 C. 6 2 3 D. 6 3 3 99 Q.33 Which of the following reactions will occur when aluminium powder is added to silver nitrate solution ? (1) displacement (2) anodization (3) redox A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 99 Q.36 The equation below represents the reaction of chlorine with hot concentrated potassium hydroxide solution:

3Cl2(g) + 6KOH(aq) → 5KCl(aq) + KClO3(aq) + 3H2O(ℓ) Which of the following statements concerning this reaction is/are correct ? (1) Potassium hydroxide acts as a reducing agent. (2) The oxidation number of chlorine changes from 0 to -1. (3) The oxidation number of chlorine changes from 0 to +5. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only


99 Q.40 Consider the following chemical cell:

Which of the following changes would lead to an increase in the voltage of the cell ? (1) The zinc electrode is replaced with a magnesium electrode. (2) The copper electrode is replaced with an iron electrode. (3) The sodium chloride solution is replaced with a sugar solution. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 99 Q.42 Consider the following experiment:

Which of the following statements concerning the experiment are correct ? (1) Gas bubbles are evolved at electrode X. (2) An orange colour gradually appears in the solution around .electrode Y. (3) The experiment can be used to show that ions migrate towards oppositely charged

electrodes. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)


00 Q.5 Which of the following gases are the major products liberated in the electrolysis of concentrated sodium chloride solution using carbon electrodes?

Cathode Anode A. Hydrogen Chlorine B. Chlorine Hydrogen C. Hydrogen Oxygen D. Oxygen Hydrogen 00 Q.28 Which of the following changes is NOT a redox reaction ? A. Fe2(SO4)3 + H2S → 2FeSO4 + S + H2SO4 B. 2Al + 6HCl → 2AlCl3 + 3H2 C. CaCO3 + CO2 + H2O → Ca(HCO3)2 D. 2KClO3 → 2KCl + 3O2 00 Q.30 In which of the following substances does nitrogen has the smallest oxidation number ? A. NH3 B. NO C. N2O D. N2


00 Q.35 Consider the chemical cell shown below:

Which of the following statements concerning the cell is/are correct ? (1) Oxidation takes place at the copper electrode. (2) The concentration of magnesium ions in beaker X increases. (3) The salt bridge allows electrons to flow from one electrode to the other electrode. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 00 Q.43 Which of the following statements concerning a zinc-carbon cell are correct ? (1) The ammonium chloride in the cell acts as an electrolyte. (2) The manganese(IV) oxide in the cell acts as an oxidizing agent. (3) The zinc case of the cell acts as the positive terminal. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 01 Q.8 Which of the following statements concerning the formation of chloride ions from chlorine atoms is correct ? A. The number of shells occupied by electrons in a chlorine atom equals that in a chloride ion.B. The atomic number of chlorine increases by 1. C. The mass number of chlorine increases by 1. D. The change is an oxidation.


01 Q.22 Which of the following equations represents a redox reaction ? A. NH4

+(aq) + OH-(aq) → NH3(g) + H2O(l) B. 2CrO4

2-(aq) + 2H+(aq) → Cr2O7 2-(aq) + H2O(l)

C. 2FeSO4(s) → Fe2O3(s) + SO3(g) + SO2(g) D. 2NaHCO3(s) → Na2CO3(s) + H2O(l) + CO2(g) 01 Q.24 Consider the half equation :

IO3-(aq) + xH2O(l) + ye- → I-(aq) + zOH-(aq)

Which of the following combinations is correct ? x y z A. 1 2 2 B. 2 4 4 C. 3 6 6 D. 4 8 8 01 Q.29 The oxidation number of lead in [Pb(OH)4]2-is A. -2. B. +2. C. +4. D. +6. 01 Q.44 Consider the set-up shown below:

Which of the following statements are correct ? (1) The solution around electrode X turns brown. (2) The mass of electrode X remains unchanged. (3) Reduction occurs at electrode Y. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)


Directions: 98 Questions 4 and 5 refer to the following experiment: The circuit shown below is set up and the solid lead(II) bromide is heated until it becomes molten.

98 Q.4 Which of the following statements concerning the experiment is INCORRECT?

A. The bulb lights up. B. A reddish brown gas is liberated at electrode X C. Electrodes X and Y can be made of nichrome D. Oxidation occurs at electrode Y. 98 Q.5 Which of the following can be deduced from the experimental results? A. Solid lead(II) bromide contains mobile ions. B. Molten lead(II) bromide contains delocalized electrons C. Molten lead(II) bromide can be decomposed by electricity. D. Solid lead(II) bromide is a covalent compound but molten lead(II) bromide is an ionic

compound. 98 Q.21 Consider the following experiment. Which of the following statements concerning the above experiment is correct?

A. Permanganate ions migrate into the salt bridge. B. Electrons flow from electrode X to electrode Y in the external circuit. C. Carbon electrodes are used because they are chemically inert D. The half equation for the change occurring at electrode Y is Fe2+ + 2e → Fe


98 Q.22 In which of the following reactions does the underlined substance act as a reducing agent? A. SO2 + 2H2S → 3S + 2H2O B. Pb(NO3)2 + H2SO4 → PbSO4 + 2HNO3 C. 2HCl + MgO → MgCl2 + H2O D. 2KBr + Cl2 → 2KCl + Br2 98 Q.27 Consider the following chemical equation:

Zn + pMnO2 +

qNH4+ → Zn2+ + xMn2O3 + yNH3 + zH2O

Which of the following combinations is correct? X y z A. 1 2 1 B. 1 3 2 C. 2 3 2 D. 2 2 3 99 Q.6 The concentration of an aqueous solution of an acid is 1.0 m. 25.0 cm3 of this acid solution requires 37.5 cm3 of 2.0 M sodium hydroxide solution for complete neutralization. What is the basicity of the acid? A. 1 B. 2 C. 3 D. 4 99 Q.12 Consider the electrolysis experiment shown below: Which of the following statements concerning this experiment is correct? A. The mass of the impure copper rod deceases. B. The blue colour of the copper(II) sulphate solution gradually fades off. C. Oxidation takes place at the pure copper rod. D. The electrolysis process can enhance the corrosion resistance of copper.


99 Q.40 Consider the following chemical cell:

Which of the following changes would lead to an increase in the voltage of the cell?

(1) The zinc electrode is replaced with a magnesium electrode. (2) The copper electrode is replaced with an iron electrode. (3) The sodium chloride solution is replaced with a sugar solution.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 00 Q.5 Which of the following gases are the major products liberated in the electrolysis of concentrated sodium chloride solution using carbon electrodes? Cathode Anode A. hydrogen chlorine B. chlorine hydrogen C. hydrogen oxygen D. oxygen hydrogen 00 Q.28 Which of the following changes is NOT a redox reaction? A. Fe2(SO4)3 + H2S → 2FeSO4 + S + H2SO4 B. 2Al + 6HCl → 2AlCl3 + 3H2 C. CaCO3 + CO2 + H2O → Ca(HCO3)2 D. 2KClO3 → 2KCl + 3O2 00 Q.30 In which of the following substances does nitrogen has the smallest oxidation number? A. NH3 B. NO C. N2O D. N2


00 Q.35 Consider the chemical cell shown below: Which of the following statements concerning the cell is/are correct?

(1) Oxidation takes place at the copper electrode. (2) The concentration of magnesium ions in beaker X increases. (3) The salt bridge allows electrons to flow from one electrode to the other electrode.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 00 Q.43 Which of the following statements concerning a zinc-carbon cell are correct?

(1) The ammonium chloride in the cell acts as an electrolyte. (2) The manganese(IV) oxide in the cell acts as an oxidizing agent. (3) The zinc case of the cell acts as the positive terminal.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 01 Q.6 When potassium carbonate solution and calcium chloride solution are mixed, calcium carbonate is precipitated. Which of the following mixtures would produce the greatest amount of precipitate? A. 5cm3 of 1 M K2CO3(aq) + 15 cm3 of 1 M CaCl2(aq) B. 10 cm3 of 1 M K2CO3(aq) + 10 cm3 of 1 M CaCl2(aq) C. 15 cm3 of 1 M K2CO3(aq) + 8 cm3 of 1 M CaCl2(aq) D. 18 cm3 of 1 M K2CO3(aq) + 5 cm3 of 1 M CaCl2(aq)


01 Q.11 Which of the following pairs of solutions, when mixed, would produce a precipitate? A. lead(II) nitrate and sodium hydroxide B. copper(II) sulphate and sodium nitrate C. zinc chloride and potassium nitrate D. iron(II) sulphate and acidified potassium permanganate 01 Q.19 Consider the half equations of a redox reaction:

8H+(aq) + MnO4

-(aq) + 5e- → Mn2+

(aq) + 4H2O(l) C2O4

2-(aq) → 2CO2(g) + 2e-

How many moles of MnO4-(aq) ions will react completely with one mole of C2O4

2-(aq) ions?

A. 0.4 B. 1.0 C. 2.5 D. 5.0 01 Q.22 Which of the following equations represents a redox reaction? A. NH4

+(aq) + OH-

(aq) → NH3(g) + H2O(l) B. 2CrO4

2-(aq) + 2H+

(aq) → Cr2O7 2-

(aq) + H2O(l) C. 2FeSO4(s) → Fe2O3(s) + SO3(g) + SO2(g) D. 2NaHCO3(s) → Na2CO3(s) + H2O(l) + CO2(g) 01 Q.23 Phosphoric acid is a tribasic acid with formula H3PO4. Which of the following formulae is INCORRECT? A. CaH2PO4 B. Mg3(PO4)2 C. (NH4)2HPO4 D. Na2HPO4 01 Q.24 Consider the half equation:

IO3-(aq) + xH2O(l) + ye- → I-

(aq) + zOH-(aq)

Which of the following combinations is correct? x y z A. 1 2 2 B. 2 4 4 C. 3 6 6 D. 4 8 8


01 Q.29 The oxidation number of lead in [Pb(OH)4]

2-is A. –2 B. +2 C. +4 D. +6 01 Q.44 Consider the set-up shown below: Which of the following statements are correct ?

(1) The solution around electrode X turns brown. (2) The mass of electrode X remains unchanged. (3) Reduction occurs at electrode Y.

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 02 Q.10 Consider the set-up shown below:

Electrons flow from X to Y in the external circuit. Which of the following combinations is correct? X Y Z A. carbon silver silver nitrate solution B. Zinc magnesium magnesium sulphate solution C. carbon carbon copper(II) sulphate solution D. Zinc carbon silver nitrate solution


02 Q.13 Which of the following equations represents a redox reaction? A. Ca(HCO3)2 + 2HCl → CaCl2 + 2CO2 + 2H2O B. PCl3 + Cl2 → PCl5 C. Fe3+ + 3OH- → Fe(OH)3 D. Al2O3 + 2NaOH → 2NaAlO2 + H2O 02 Q.18 The symbol of vanadium is V. What is the oxidation number of vanadium in NH4VO3? A. -1 B. +3 C. +5 D. +6 02 Q.47 During electrolysis, oxidation takes place at the cathode.

Cations accept electrons and are dischargedat the cathode.

1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st one. B. True True 2nd statement is NOT a correct explanation of the 1st one.C. True/False False/True Only ONE of the statements is true, the other is false. D. False False ----- 03 Q.3 When a small piece of calcium metal is put into a trough of water, a reaction occurs. Which of the following statements concerning this reaction is correct? A. It is an endothermic reaction. B. It is a redox reaction. C. A slight explosion occurs. D. The calcium metal burns spontaneously

in water. 03 Q.5 Which of the following methods can be used to obtain aluminium from aluminium oxide? A. reducing the oxide with carbon B. heating the oxide strongly C. electrolysis of the molten oxide D. heating the oxide with iron powder 03 Q.15 In the electrolysis of a copper(II) sulphate solution, copper is used as the anode and carbon as the cathode. Which of the following statements concerning this electroysis is correct? A. The concentration of Cu2+(aq) ions in the solution remains unchanged. B. The concentration of H+(aq) ions in the solution increases. C. O2(g) is liberated at the anode. D. H2(g) is liberated at the cathode.


03 Q.16 Which of the following conversions is NOT a reduction? A. Fe2O3 → Fe B. Cu(OH)2 → CuO C. CH3COOH → CH3CH2OH D. H2SO4 → SO2 03 Q.18 Consider the following information about three elements, X, Y and Z.

Element Atomic number X 12 Y 16 Z 17

Which of the following statements concerning X, Y and Z is correct? A. X reacts with Z to form an ionic compound. B. Y is a stronger oxidizing agent than Z. C. X has a simple molecular structure. D. Y can conduct electricity in the molten state. 03 Q.24 What is the oxidation number of sulphur in H2S2O7? A. +2 B. +4 C. +6 D. +8 03 Q.35 Which of the following is/are advantage(s) of using alkaline manganese cells over sinc- carbon cells in cassette players?

(1) Alkaline manganese cells have longer life time. (2) Alkaline manganese cells are rechargeable.

(3) Alkaline manganese cells give a more steady voltage over discharge. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only


M.C. Answer 85 86 87 88 89 90 91 92 93 5 B 1 C 10 C 1 D 10 C 1 A 6 B 4 A 15 B 14 A 6 C 11 B 32 C 12 D 5 A 7 C 9 A 16 C 15 D 12 B 12 B 38 C 13 A 19 C 9 C 10 C 17 D 40 D 13 C 14 D 14 D 23 B 14 A 12 B 19 C 41 A 14 B 39 C 29 A 24 B 43 D 37 B 24 C 53 C 17 B 42 B 30 C 46 B 54 B 20 D 43 D 38 B 33 C 39 A 42 D 94 95 96 97 98 99 00 01 02 4 A 10 A 7 C 4 C 4 B 6 C 5 A 6 B 10 D 12 C 11 D 25 B 7 D 5 C 12 A 28 C 11 A 13 B 13 B 24 D 27 D 8 B 21 C 40 A 30 A 19 A 18 C 17 A 30 B 30 A 11 D 22 D 35 B 22 C 47 C 34 B 32 B 31 D 27 A 43 A 23 A 33 D 35 C 24 C 37 B 42 C 29 B 40 C 46 D 44 D 03 3 5 15 16 18 24 35

85 q.5 a. an oxidizing agent. 85 q.14 a. nh cl b. no c. hno d. n …€¦ · 03-05-2009 ·...

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