Chemistry 2014 JAMB Past Questions

Chemistry 2014 JAMB Past Questions

 

 

1. A mixture is different from a compound because
  • A. the properties of a compound are those of its individual constituents while those of a mixture differ from its constituents
  • B. a mixture is always homogeneous while a compound is not
  • C. the constituent of a compound are chemically bound together while those of a mixture are not
  • D. a mixture can be represented by a chemical formula while a compound cannot
Correct Answer: Option C
 
2. What is the percentage of sulphur in sulphur (IV) oxide?
  • A. 66%
  • B. 25%
  • C. 40%
  • D. 50%
Correct Answer: Option D
Explanation
molar mass of SO 2=64 :.%S=32/64 x 100 = 50%
 
 
3. A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y.
  • A. 128
  • B. 8
  • C. 16
  • D. 64
Correct Answer: Option A
Explanation
RYRX = √My√My 1/2 = √32√y 32y = 1/4
Y = 32x41 = 128
 
4. 200 cm3 of a gas at 25oC exerts a pressure of 700 mmHg. Calculate its pressure if its volume increase 350 cm3 at 75oC.
  • A. 342.53 mmHg
  • B. 1430.54 mmHg
  • C. 467.11 mmHg
  • D. 400.00 mmHg
Correct Answer: Option C
Explanation
\(\frac{p 1V 1}T 1\) = \(\frac{P 2V 2}{T 2}\) = \(\frac{P2X 350}{348}\) P2 = = 467.11mmHg
 
5. An element X has electron configuration 1s2 2s2 2p6 3s2 3p5. Which of the following statements is correct about the element?
  • A. lt has a completely filled p-orbital
  • B. lt has 5 electrons in its outermost shell.
  • C. lt belongs to group ll on the periodic table
  • D. lt is a halogen
Correct Answer: Option D

6. Beryllium and aluminium have similar properties because they
  • A. are both metals
  • B. belong to the same group
  • C. belong to the same period
  • D. are positioned diagonally to each other
Correct Answer: Option D
Explanation
At the beginning of periods 2 and 3 of the Periodic Table, there are several cases where an element at the top of one group has some similarities with an element in the next group.
For example, boron is a non-metal with some properties rather like silicon. Unlike the rest of Group 2, beryllium has some properties resembling aluminium. And lithium has some properties which differ from the other elements in Group 1, and in some ways resembles magnesium.

There is said to be a diagonal relationship between these elements.

There are several reasons for this, but each depends on the way atomic properties like electronegativity vary around the Periodic Table.
 
 
7. If the difference in electronegativity of elements P and Q is 3.0. The bond that will be formed between them is
  • A. metallic
  • B. covalent
  • C. co-ordinate
  • D. ionic
Correct Answer: Option D
8. How many protons, neutrons and electrons respectively are present in the element 60/27 Co?
  • A. 27, 33 and 33
  • B. 33, 27 and 27
  • C. 27, 33, and 27
  • D. 60, 33 and 60
Correct Answer: Option D
9.The radio active radiation used in studying the arrangement of particles in giant organic molecules is
  • A. - rays
  • B. - particles
  • C. X-rays
  • D. - particles
    • Correct Answer: Option C
     
    10. A silicon -containing ore has 92% 28Si, 5% 29Si and 3% 30Si. Calculate the relative atomic mass of the silicon.
    • A. 14.00
    • B. 29.00
    • C. 28.11
    • D. 28.00
    Correct Answer: Option C
    Explanation
    ( x 28) + ( x 29) + ( x 230) = 28.11
     
    11. The nitrogen obtained from air has a density higher than the one from nitrogen-containing compounds because the one from air is contaminated with
    • A. water vapour
    • B. oxgyen
    • C. rare gases
    • D. carbon (IV) oxide
    Correct Answer: Option C
    12. Water is said to be temporarily hard when it contains
    • A. Ca (HCO3)2 and Mg (HCO3)2 salts
    • B. Ca (HCO3)2 and CaCO3 SALTS
    • C. Mg(HCO3)2 and CaSO4 salts
    • D. CaSO4 and Ca(HCO3)2 salts
    Correct Answer: Option A
     
    13. On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as
    • A. efflorescence
    • B. diliquescence
    • C. hygroscopy
    • D. hydrolysis
    Correct Answer: Option A
     
    14. 16.55g of lead (ll) trioxonitrate (V) was dissolved in 100g of distilled water at 20oC, calculate the solubility of the solute in moldm-3

    [Pb = 207, N = 14, O = 16]
    • A. 0.05 g
    • B. 2.00 g
    • C. 1.00 g
    • D. 0.50g
    Correct Answer: Option D
    Explanation
    molar mass of pb (N0 3) 2 = 331
    Mole =
    = 0.05 mole
    ∴0.05mole pb (No3)2 dissolved in 1000g H2O x = = 0.5 mole /dm 3
     
     
    15. The dispersion of a liquid in a liquid medium will give
    • A. an emulsion
    • B. a fog
    • C. a gel
    • D. an aerosol 

    Correct Answer: Option A

    16. The major and most effective way of controlling pollution is to
    • A. improve machinery so that the substances released from combustion are less harmful
    • B. pass strict laws against it by individuals and companies
    • C. educate people on the causes and effects of pollution
    • D. convert chemical wastes to harmless substances before releasing them into the environment
    Correct Answer: Option C
     
    17. The basicity of CH3COOH is
    • A. 4
    • B. 1
    • C. 2
    • D. 3
    Correct Answer: Option B
    18. The colour of litmus in a neutral medium is
    • A. purple
    • B. pink
    • C. yellow
    • D. orange 

    Correct Answer: Option A
    19. The mathematical expression of PH is
    • A. log 10[OH-]
    • B. log 101/[H 3 O+]
    • C. log 10[H 3 O+]
    • D. log 101/[OH -]
    Correct Answer: Option B
    20. Which of the following salts will turn blue litmus red?
    • A. Sodium tetrahydroxozincate (ll)
    • B. Potassium hydrogentetraoxosulphate (lV)
    • C. Sodium trioxocarbonate (lV)
    • D. Zinc chloride hydroxide 

    Correct Answer: Option B

    21. Zn (s) + CuSO 4(aq) → ZnSO 4(aq) + Cu (s)
    In the reaction above, the oxidation number of the reducing agent changes from
    • A. 0 to + 4
    • B. 0 to + 2
    • C. + 1 to + 2
    • D. + 1 to + 3
    Correct Answer: Option B
     
    22. H 2O (g) + C (s) → H2(g) + CO(g)

    The oxidizing agent in the reaction above is
    • A. CO(g)
    • B. C(s)
    • C. H2O(g)
    • D. H(2)(g)
    Correct Answer: Option C
     
    23. Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound

    [Cu=64, F = 96500 Cmol-1]
    • A. 32395.5
    • B. 30156.3
    • C. 60784.5
    • D. 15196.5
    Correct Answer: Option B
    Explanation
    Cu → Cu2++ 2e
    64g Cu requires 2 x 96500 coloumbs 10g Cu requires x columbs
    x = 10x2x96500/64 =30156.3
     
     
    24. How many faraday of electricity is required to produce 0.25 mole of copper?
    • A. 1.00F
    • B. 0.01F
    • C. 0.05F
    • D. 0.50F 

    Correct Answer: Option D
    Explanation
    Cu → Cu2+ + 2e
    1mole Cu requires 2f
    0.25 mole Cu requires x
    x = 0.25x2/1 = 0.50f
     
     
    25. If the change in free energy of a system is -899 Jmol-1 and the entropy change is 10Jmol-1k-1 at 250C, calculate the enthalpy change.
    • A. +2081 Jmol-1
    • B. -2081 Jmol-1
    • C. -649 Jmol-1
    • D. +649 Jmol-1
    • Correct Answer: Option A
      Explanation
      ∆G = ∆H - T∆S
      -899 = ∆H - 2980
      ∆H = -899 + 2980 = + 2081 Jmol-1

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