JAMB - Chemistry (1979)

• 1

  An organic compound X has the following properties: I. It is not miscible with water. ll. lt has boiling point of 77^oC lll. lt has a sweet odour lV. lt is insoluble in sodium hydrogen carbonate solution . V lt does not decolourize bromine water X is therefore

  回答

  (D)

  ethyl ethanoate
• 2

  Which are the correct IUPAC names for H-CO\(_2\)CH\(_3\) and CH \(\equiv\) CH

  回答

  (D)

  Methyl methanoate and ethyne
• 3

  Which of the following substances are all made by the process of polymerization?

  回答

  (C)

  Nylon and artificial rubber
• 4

  The reaction of zinc with copper (ll) ions in aqueous solution can be represented as follows: Cu ²⁺(aq) +Zn (s) → Cu(s) + Zn ²⁺(aq).Which of the following is the most complete description of this reaction?

  回答

  (E)

  copper(ll) ions are being reduced and zinc oxidized
• 5

  The oxidation state of manganese in potassium permanganate is

  回答

  (A)

  +7
• 6

  When carbondioxide is bubbled into limewater a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is

  回答

  (C)

  calcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate
• 7

  Methanoic acid mixes with water in all proportions and has about the same boiling point as water which of the following methods would you adopt to obtain pure water from a mixture of stand, water and methanoic acid?

  回答

  (E)

  neutralization with sodium hydroxide followed by filtration
• 8

  Which of the following statements applies during the electrolysis of sodium hydroxide solution using platinum electrodes?

  回答

  (B)

  Hydrogen ions are discharged at the cathode
• 9

  Which of the following statements is true? When the potassium atom forms its ion

  回答

  (C)

  it achieves electronic configuration of orgon
• 10

  Which of the following contains two amphoteric oxides?

  回答

  (B)

  Aluminium oxide, Calcium oxide, Zinc oxide
• 11

  Helium atoms are chemically unreactive because

  回答

  (D)

  the outer electron shell is completely filled
• 12

  \(50cm^{3}\) of hydrogen are sparked with \(20cm^{3}\) of oxygen at \(100°C\) and \(1atm\) . The total volume of the residual gases in

  回答

  (A)

  50 cm³
• 13

  How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80)

  回答

  (C)

  8. 1g
• 14

  When ammonium, potassium and calcium carbonates are each separately heated

  回答

  (E)

  ammonium carbonate will decompose to give carbondioxide, water and ammonia
• 15

  If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while

  回答

  (E)

  the solution will give out oxygen gas leaving behind aqueous hydrochloric acid
• 16

  12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 oC. The solubility of potassium chlorate at 66 oC is therefore?

  回答

  (E)

  30
• 17

  In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:
  Anode Cathode

  回答

  (C)

  Oxygen Hydrogen
• 18

  The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0)

  回答

  (C)

  NO₂
• 19

  When a piece of charcoal enclosed in a cylinder containing air is ignited

  回答

  (D)

  the relative amount of carbondioxide present is increased
• 20

  Indicate which of the following statements is not true as we move from left to right along the periodic Table:

  回答

  (C)

  electropositive character of elements increases
• 21

  0.1 Faraday of electricity was passed through a solution of copper (ll) sulphate. The maximum weight of copper deposited on the cathode would be [Cu = 64]

  回答

  (E)

  3.2g
• 22

  Which one of these compounds will NOT give an oxygen gas on heating?

  回答

  (E)

  Ammonium nitrate
• 23

  In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because

  回答

  (B)

  it makes bauxite melt at a lower temperature
• 24

  In the redox reaction\( 2Fe^{2+} + CI_2 → 2Fe^{3+} + 2Cl^-\)

  回答

  (B)

  Cl₂ is reduced because its oxidation number has decreased
• 25

  An anhydride is?

  回答

  (C)

  an oxide whose solution in water has a PH less than 7
• 26

  In which of the following reactions is sulphur dioxide acting as an oxidizing agent?

  回答

  (D)

  SO₂ + 2H₂S → 3S + 2H₂O
• 27

  Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by

  回答

  (C)

  passing it through calcium oxide
• 28

  Starch can be converted to ethyl alcohol by

  回答

  (B)

  fermentation
• 29

  The reaction between hydrogen and iodine may be represented by the equation H₂(g)+ I₂(g) → 2HI(g), and is exothermic. Therefore

  回答

  (D)

  a decrease in temperature will favour the forward reaction
• 30

  Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts?

  回答

  (D)

  Y and Z are hygroscopic
• 31

  In the manufacture of iron in the blast furnace, iron (lll) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions?

  回答

  (E)

  the calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity
• 32

  Which of the following statements is true?

  回答

  (D)

  a increase in the pressure of a gas is proportional to the decrease in volume at constant temperature
• 33

  the vapour density of a gas may be defined as

  回答

  (B)

  the mass of a unit volume of the gas compared to an equal volume of hydrogen
• 34

  The reaction 3C(s) + 2Fe₂O₃(s) = 4Fe(s) + 3CO₂(g): \(\Delta\)H =46.0 kJ is

  回答

  (D)

  endothermic
• 35

  The solution of a sample in a tube will be identified as a chloride if it gives

  回答

  (C)

  a white precipitate when acidified with dilute HNO₃ and then AgNO₃ solution added
• 36

  Hydrogenation may be effected by

  回答

  (C)

  the addition of hydrogen to an alkyne
• 37

  Two metallic ions associated with hard water are

  回答

  (C)

  calcium and magnesium
• 38

  Bronze is an alloy of

  回答

  (E)

  tin and copper
• 39

  Phosphorus burns in oxygen according to the equation P\(_4\) + 5 0\(_2\) → P\(_4\)O\(_{10}\). How many litres of oxygen will be required at S.T.P for complete oxidation of 12.4g of phosphorus? [P = 31,O = 16 and molar volume of a gas at S.T.P = 22.4 litres]

  回答

  (B)

  11. 20
• 40

  On heating anhydrous iron (ll) sulphate, in addition to producing iron (iii) oxide, which of the following is produced?

  回答

  (C)

  SO₂ (g) + SO₃(g)
• 41

  One of the following techniques can be used to show that chlorophyll pigment is a mixture of chemical compounds and not a single coloured compound

  回答

  (E)

  chromatography
• 42

  A gas occupies a volume of 30.0 dm\(^3\) at S.T.P. What volume would it occupy at 91\(^0\)C and 380 mm Hg?

  回答

  (D)

  80. 0dm³
• 43

  When excess ethanol is heated to 145 ^oC in the presence of concentrated sulphuric acid, the product is

  回答

  (A)

  diethyl ether
• 44

  Which of the following raw materials would be required from the smelting of iron ore in a blast furnace?

  回答

  (A)

  CaCO ₃
• 45

  A piece of metal (M) is dissolved in nitric acid and the resulting solution is treated with a small quantity of sodium hydroxide to produce a white precipitate (B) which redissolves on the addition of excess alkali. The precipitate (B)when ignited in a crucible produces the oxide of the metal(m). The METAL M is

  回答

  (A)

  Zn