In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because
- A. it makes bauxite a better conductor of electricity
- B. it makes bauxite melt at a lower temperature
- C. it makes aluminium purer
- D. it prevents aluminium from getting oxidized
- E. it protects the carbon electrodes used in the process
Which one of these compounds will NOT give an oxygen gas on heating?
- A. Manganese dioxide
- B. Hydrogen peroxide
- C. Zinc nitrate
- D. Sodium nitrate
- E. Ammonium nitrate
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]
- A. 64.0g
- B. 32.0g
- C. 16.0g
- D. 6.4 g
- E. 3.2g
Indicate which of the following statements is not true as we move from left to right along the periodic Table:
- A. atomic number of elements increases
- B. atomic mass of elements increases
- C. electropositive character of elements increases
- D. electronegative character of elements increases
- E. number of electrons in the outermost orbits of element increases
When a piece of charcoal enclosed in a cylinder containing air is ignited
- A. the toatl volume of air is increased
- B. the relative amount of oxygen present is increased
- C. the relative amount of nitrogen present is decreased
- D. the relative amount of carbondioxide present is increased
- E. the ratio of oxygen to nitrogen in the system is increased
The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0)
- A. N2O2
- B. NO
- C. NO2
- D. N2O
- E. N2O3
In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:
Anode Cathode
- A. Sulphur hydrogen
- B. Hydrogen oxygen
- C. Oxygen Hydrogen
- D. Hydrogen sulphate ions
- E. Sulphur oxygen
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?
- A. 66
- B. 33
- C. 10
- D. 20
- E. 30
If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while
- A. the solution will give out chlorine gas and hydrogen chloried gas
- B. the solution will produce chlorine gas and oxygen
- C. the solution will give out solution will producing hypochloric acid
- D. the solution is decomposed giving out oxygen, hydrogen and chlorine
- E. the solution will give out oxygen gas leaving behind aqueous hydrochloric acid
When ammonium, potassium and calcium carbonates are each separately heated
- A. none of them will decompose
- B. each of them will decompose to give carbondioxide and the respective oxide
- C. ammonium carbonate and potassium carbonate will not decompose
- D. only ammonium carbonate and the respective oxide
- E. ammonium carbonate will decompose to give carbondioxide, water and ammonia
How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80)
- A. 4. 1 g
- B. 6. 1 g
- C. 8. 1g
- D. 16.2g
\(50cm^{3}\) of hydrogen are sparked with \(20cm^{3}\) of oxygen at \(100°C\) and \(1atm\) . The total volume of the residual gases in
- A. 50 cm3
- B. 10 cm3
- C. 40 cm3
- D. 30 cm3
- E. 70 cm3
Helium atoms are chemically unreactive because
- A. there are no electrons around the nucleus
- B. the number of protons equals the number of electrons
- C. there are equal number of protons and neutrons in the nucleus
- D. the outer electron shell is completely filled
- E. the atoms contain only protons
Which of the following contains two amphoteric oxides?
- A. sodium oxide, Zinc oxide , Magnesium oxide
- B. Aluminium oxide, Calcium oxide, Zinc oxide
- C. Potassium oxide, Lithium oxide, Carbon monoxide
- D. Silver oxide, Lead oxide, Sodium oxide
- E. Sulphur dioxide, Aluminium oxide, Carbon monoxide
Which of the following statements is true? When the potassium atom forms its ion
- A. it gains one electron and becomes neutral
- B. its atomic number decreases
- C. it achieves electronic configuration of orgon
- D. it loses one proton
- E. it loses one neutron
Which of the following statements applies during the electrolysis of sodium hydroxide solution using platinum electrodes?
- A. Na+ ions are discharged at the cathode
- B. Hydrogen ions are discharged at the cathode
- C. the concentration of sodium hydroxide decrease at both electrode compartments
- D. the concentration of sodium hydroxide increases at the cathode only
- E. the concentration of sodium hydroxide increases at the anode only
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?
- A. fractional distillation
- B. filtration followed by distillation
- C. neutralization with sodium hydroxide followed by distillation
- D. esterification with ethanol followed by distillation
- E. neutralization with sodium hydroxide followed by filtration
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
- A. calcium carbonate is formed which on reaction dissolves
- B. calcium hydrogen carbonate is precipitated and then dissolves
- C. calcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate
- D. concentration of the solution has occurred with the deposition of calcium hydroxide
- E. the solution has become saturated and solid carbondioxide has been deposited
The oxidation state of manganese in potassium permanganate is
- A. +7
- B. +5
- C. +3
- D. +2
- E. +1
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?
- A. Cpper (ll) ions are being reduced
- B. Zinc is being oxidized.
- C. Copper (ll) ions and zinc are being reduced
- D. copper (ll) ions and zinc are being oxidized
- E. copper(ll) ions are being reduced and zinc oxidized
Which of the following substances are all made by the process of polymerization?
- A. Nylon and soap
- B. Ethanoic acid margarine and ethanol
- C. Nylon and artificial rubber
- D. Soap and butane
- E. Margarine and nylon