JAMB UTME - Chemistry - 1979

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

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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

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

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The solution of a sample in a tube will be identified as a chloride if it gives a white precipitate when acidified with dilute HNO3 and then AgNO3 solution is added. This is because the test is a confirmatory test for chloride ions, and the white precipitate formed is silver chloride (AgCl). Chloride ions react with silver nitrate (AgNO3) to form a white precipitate of AgCl, which is insoluble in water and dilute nitric acid.

Two metallic ions associated with hard water are

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

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

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When ammonium, potassium and calcium carbonates are each separately heated

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

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Hydrogenation may be effected by

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Consider the following exothermic reaction 2SO₂(g) + O₂(g) = 2SO₃ (g) . If the temperature of the reaction is reduced from 800_oC to 500_oC, and no other change takes place, then

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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?

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

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Phosphorus burns in oxygen according to the equation P₄ + 50₂ → P₄O₁₀. 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]

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

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An anhydride is

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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?

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

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Which are the correct IUPAC names for H-CO₂CH₃ and CH = CH

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Which of the structural formal above is ethanoic acid is

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Which of the following statements is true?

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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

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Helium atoms are chemically unreactive because

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

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Pick out the correct statement

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

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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]

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

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

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

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The oxidation state of manganese in potassium permanganate is

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Bronze is an alloy of

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The IUPAC name for

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

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

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

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

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In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl

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

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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

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Which of the following contains two amphoteric oxides?

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Starch can be converted to ethyl alcohol by

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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?

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the vapour density of a gas may be defined as

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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

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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?

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A gas occupies 30.0 dm³ at S.T.P. What volume would it occupy at 91^oC and 380 mm Hg?

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

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

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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

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