www.prep.ng: JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2012 (TEXT)

Saturday, 2 March 2019

JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2012 (TEXT)


PAPER TYPE: RED

 1.      Which Question Paper Type of Chemistry is given to you?
A.      Type Green
B.      Type Purple
C.      Type Red
D.     Type Yellow

 2.      Which of the following methods can be used to obtain pure water from a mixture of sand, water and methanoic acid?
A.      neutralization with NaOH followed by filtration
B.      neutralization with NaOH followed by distillation
C.      fractional distillation
D.     filtration followed by distillation

 3.      How many atoms are present in 6.0g of magnesium?
[Mg = 24, NA = 6.02 x 1023 mol-1]
A.      1.20 x 1022
B.      2.41 x 1022
C.      1.51 x 1023
D.     3.02 x 1023

 4.      50 cm3 of gas was collected over water at 10oC and 765 mm Hg. Calculate the volume of the gas at s.t.p. if the saturated vapour pressure of water at 10 oC is 5mm Hg
A.      49.19 cm 3
B.      48.87 cm 3
C.      48.55 cm 3
D.     48.23 cm 3

 5.      An increase in the pressure exerted on gas at a constant temperature result in ___.
A.      a decrease in the number of effective collisions
B.      a decrease in volume
C.      an increase in the average inter-molecular distance
D.     an increase in volume

 6.      2H2(g) + O2(g)  2H2 O(g)
In the reaction above, what volume of hydrogen would be left over when 300 cm3 of oxygen and 1000 cm3 of hydrogen are exploded in a sealed tube?
A.      200 cm3
B.      400 cm3
C.      600 cm3
D.     700 cm3
 7.      l. Evaporation.
       ll. Sublimation.
      Ill. Diffusion.
      IV. Brownian motion.
      Which of the above can correctly be listed as evidences for the particulate nature of matter?
A.      I and lll only
B.      ll and lV only
C.      l, ll and lll only
D.     l, ll, lll and lV
 8.      If the elements X and Y have atomic numbers 11 and 17 respectively, what type of bond can they form?
A.      Dative
B.      Covalent
C.      Ionic
D.     Metallic

 9.      A hydrogen atom which has lost an electron contains ___.
A.      one proton only
B.      one neutron only
C.      one proton and one neutron
D.     one proton, one electron and one neutron

10.  The electronic configuration of Mg 2+ is ___.
A.      1s 22s 22P 63s23P2
B.      Is22s22P63s2
C.      ls22s22p6
D.     ls22s22P4

11.  Group VII elements are ___.
A.      monoatomic
B.      good oxidizing agents
C.      highly electropositive
D.     electron donors

12.  Which of the following is used to study the arrangement of particles in crystal lattices?
A.      Alpha-particles
B.      Beta-particles
C.      Gamma-rays
D.     X-rays

13.  I. It has a varied composition from one place to another.
ll. its constituents can be separated by physical means
Ill. It contains unreactive noble gases
which of the above shows that air is a mixture?
A.      I and ll only
  B.      ll and lll only
  C.      l and lll only
  D.     l, ll and lll

14.  The chemicals used to soften hard water involves the addition of ___.
A.      insoluble sodium compounds which from soluble solutions of calcium and magnesium
B.      soluble sodium compounds which from soluble solutions of calcium and magnesium ions
C.      soluble sodium compounds which from insoluble precipitates of calcium and magnesium ions
D.     insoluble precipitates of calcium and magnesium ions

15.  Chlorination of water for town supply is carried out to ___.
A.      make the water colourless
B.      remove germs from the water
C.      make the water tasteful
D.     remove odour from the water

16.  The solubilities of different solutes in a given solvent can be compared by ___.
A.      plotting their solubility curves on separate axes
B.      plotting their solubility curves on the same axes
C.      plotting some of the solubility curves on the x-axis and others on the y-axis
D.     plotting their solubility curves on the x-axis only

17.  Potassium trioxochlorate (V) has a solubility of 1.5 moldm-3 at 45 oC. On cooling this solution to a temperature of 20 oC, the solubility was found to be 0.5 mol dm -3. What mass of KCIO 3 was crystalized out?
[K = 39, Cl = 35.5 O =16]
A.      1.00g
B.      10.00g
C.      12.25g
D.     122.50g

18.  Which of the following pollutants is associated with brain damage?
A.      Carbon (ll) oxide
B.      Radioactive fallout
C.      Biodegradable waste
D.     Sulphur (lV) oxide

19.  Which of the following will produce a solution with pH less than 7 at equivalent point?
A.      HNO3 + NaOH
B.      H2SO4 + KOH
C.      HC +Mg(OH)2
D.     HNO3 + KOH

20.  The number of hydroxonium ions produced by one molecule of an acid in aqueous solution is its ___.
A.      basicity
B.      acid strength
C.      pH
D.     concentration

21.  During a titration experiment, 0.05 moles of carbon (lV) oxide is liberated. What is the volume of gas liberated?
A.      22.40 dm3
B.      11.20 dm3
C.      2.24 dm3
D.     1.12 dm3

22.  A major factor considered in selecting a suitable method for preparing a simple salt is its ___.
A.      Crystalline from
B.      melting point
C.      reactivity with dilute acids
D.     solubility in water

23.  The oxidation number of boron in NaBH4 is ___.
A.      -3
B.      -1
C.      +1
D.     +3

24.  2NaO2(s) + 2H2O2(l)  4 NaOH(s) +O2(s)
The substance that is oxidized in the reaction above is
A.      2NaO2(s)
B.      NaOH(aq)
C.      H2O(l)
D.     O2(g)

25.  What number of moles of Cu 2+ will be deposited by 360 coulombs of electricity?
[f = 96500 C mol -1]
A.      5.36 x 10-4 mole
B.      1. 87 x 10-3 mole
C.      9. 35 x 10-4 mole
D.     3. 73 x 10-3 mole

26.  A metal M displaces zinc from ZnCl, solution. This shows that ___.
A.      electrons flow from zinc to M
B.      M is more electropositive than zinc
C.      M is more electronegative than zinc
D.     zinc is more electropositive than M

27.  CO(g) + H2O(g)  CO2(g) + H2(g)
Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO2(g), H2O(g) and CO(g) and CO(g) in KJ mol-1 are -394, -242 and -110 respectively.
A.      + 262 KJ mol -1
B.      - 262 KJ mol -1
C.      + 42 KJ mol -1
D.     - 42 KJ mol -1

28.  An increase in entropy can best be illustrated by ___.
A.      mixing of gases
B.      freezing of water
C.      the condensation of vapour
D.     solidifying candle wax

29.  The highest rate of production of carbon (lV) oxide can be achieved using ___.
A.      0.05 mol -3HCI and 5g powdered CaCO3
B.      0.05 mol -3HCI and 5g lump CaCO3
C.      0.10 mol -3HCI and 5g powdered CaCO3
D.     0.025 mol -3HCI and 5g powdered CaCO3

30.   


2HCl(aq) + CaCO3(S) CaCl2(s) + CO2(g) + H2O(l)
From the reaction above, which of the curves represents the production of co2 gas as dilute HCl is added?
A.      L
B.      M
C.      N
D.     P

31. 2CO(g) + O2(g)2CO2(g)

In the reaction above, high pressure will favour the forward reaction because ___.
A.      high pressure favours gas formation
B.      the reaction is in dynamic equilibrium
C.      the reaction is exothermic
D.     the process occurs with a decrease in volume

32.  A piece of filter paper moistened with lead (ll) ethanoate solution turns black when the paper is dropped into a gas likely to be ___.
A.      sulphur (VI) oxide
B.      hydrogen chloride
C.      sulphur (VI) oxide
D.     hydrogen sulphide

33.  Which of the following gases has a characteristic pungent smell, turns red litmus paper blue and forms dense white fumes with hydrogen chloride gas?
A.      N2
B.      N2O
C.      CI2
D.     NH3

34.  Commercial bleaching can be carried out using ___.
A.      sulphur (IV) oxide and ammonia
B.      hydrogen sulphide and chlorine
C.      chlorine and sulphur (IV) oxide
D.     ammonia and chlorine

35.  Mineral acids are usually added to commercial hydrogen peroxide to ___.
A.      oxidize it
B.      decompose it
C.      minimize its decomposition
D.     reduce it to water and oxygen

36.  Which of the following compounds will burn with a brick-red colour in a non-luminous Bunsen flame?
A.      LiCI
B.      NaCl
C.      CaClN2
D.     MgClN2

37.  The purest form of iron which contains only about 0.1% carbon is ___.
A.      pig iron
B.      wrought iron
C.      cast iron
D.     iron pyrite

38.  A common characteristic between zinc and the other transition elements is the ability to ___.
A.      have variable oxidation states
B.      from complex ions
C.      act as a catalyst
D.     from coloured ions

39.  Which of the following metals is the least reactive?
A.      Pb
B.      Sn
C.      Hg
D.     Au

40.  Geometric isomerism can exist in ___.
A.      hex-3-ene
B.      hexane
C.      prop-1-ene
D.     3-methyl but -1-ene

41.  Alkanals can be distinguished from alkanones by the reaction with ___.
A.      Sudan lll stain
B.      starch iodide paper
C.      lithium tetrahydrido aluminate (lll)
D.     Fehling’s solution

42.  The isomers of C3H8O are ___.
A.      1 - propanol and 2 - propanol
B.      1 - propanol and 1 - propanol
C.      2 - propanol and 2 - propanone
D.     2 - propanol and 1 - propanol

43.  Carbohydrates are large molecules with the molecular formula Cx (H2O)y. In which of the following pairs is x not equal to y?
A.      glucose and starch
B.      maltose and starch
C.      sucrose and fructose
D.     maltose and starch

44.  A compound contains 40.0% C, 6.7% H 53.3% O. If the molecular mass of the compound is 180, its molecular formula is [C =12, H =1, 0]
A.      CH2O
B.      C3H6O3
C.      C6H6O3
D.     C6H12O6

45.  The alkyne that will give a white precipitate silver trioxonitrate (V) is ___.
A.      CH3 CH2C ≡ C CH2 CH3
B.      CH3 C ≡ C CH2 CH2 CH3
C.      CH3 CH2 CH2 CH2C ≡ CH
D.     CH3 CH2 CH2C ≡ C CH2 CH3

46.  The saponification of an alkanoate to produce soap and alkanol involves
A.      dehydration
B.      esterification
C.      hydrolysis
D.     oxidation

 47.  2 - methyl propan -2- ol is an example of a ___.
A.      primary alkanol
B.      secondary alkanol
C.      tertiary alkanol
D.     quaternary alkanol

48.  The final oxidation product of alkanol, alkanal and alkanoes is ___.
A.      alkanoic acid
B.      alkanoyyl halide
C.      alkanoate
D.     alkanamide

49.  Ethanol reacts with concentrated tetraoxosulphate (V) acid at a temperature above 170oC to form ___.
A.      ethanone
B.      ethene
C.      ethyne
D.     ethanal

50.  An example of oxidation - reduction enzyme is ___.
A.      amylase
B.      protease
C.      lipase
D.     dehydrogenase

ANSWERS

1.      C
2.      D
3.      C
4.      D
5.      B
6.      B
7.      D
8.      C
9.      C
10.  C
11.  B
12.  D
13.  A
14.  C
15.  B
16.  B
17.  D
18.  B
19.  C
20.  B
21.  D
22.  D
23.  D
24.  A
25.  B
26.  B
27.  C
28.  A
29.  C
30.  Wrong diagram. No answer
31.  D
32.  D
33.  D
34.  C
35.  C
36.  C
37.  B
38.  B
39.  D
40.  A
41.  D
42.  A
43.  A
44.  D
45.  C
46.  C
47.  C
48.  A
49.  B
50.  D

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