Chemistry Past Questions And Answers
The molecule that has a non-polar covalent bond is
- A. HCl
- B. \(NH_3\)
- C. \(Cl_2\)
- D. \(H_2O\)
Which of the following combination of conditions many increase the rate of a chemical reaction?
- A) Decrease in temperature, increase in concentration of the reactant
- B) Increase in temperature, addition of a catalyst, decrease in the surface area of the reactant
- C) Increase in temperature, increase in concentration, addition of a catalyst and increase in the surface area of the reactant
- D) Decrease in temperature, concentration and surface area of the reactants
The reaction of an alkanol with an alkanoic acid in the presence of concentrated H2SO4 will produce an?
- A. alkanal
- B. alkanoate
- C. alkanone
- D. alkyne
Which of the following combination of gases is used for metal welding? i. Oxygen and ethyne, ii. Hydrogen and ethyne, iii. Hydrogen and oxygen, iv. Ethyne, hydrogen and oxygen.
- A. i and ii
- B. ii and iv
- C. i and iii
- D. ii and iv
(a)(i) State the two main processes involved in the manufacture of oxygen from air
(ii) Name the type of chemical bonding which exists between oxygen atoms in a molecule of oxygen
(b) What term is used to describe the relationship between oxygen and ozone (O\(_3\))?
View Discussion (0)WAEC 1997 THEORYThe temperature of a body decreases when drops of liquid placed on it evaporate because?
- A. the atmospheric vapour pressure has a cooling effect on the body
- B. a temperature gradient exists between the drops of liquid and the body causing the latter to vaporate
- C. the heat of vapourization is drawn from the body causing it to cool
- D. the random motion of the liquid molecules causes a cooling effect on the body
What quantity of electrons (in mole) is lost when one mole of iron (ll) ions is oxidized to iron (lll) ions?
- A. 4mole
- B. 3 mole
- C. 2 mole
- D. 1 mole
(a)(i) Name a suitable drying agent for the preparation of carbon (IV) oxide in the laboratory.
(ii) Using one chemical test, distinguish between carbon (II) oxide and carbon (IV) oxide.
(b)(i) Describe briefly how oxygen and nitrogen could be obtained separately from air on an industrial scale
(ii) State how a lighted splint can be used to distinguish between samples of oxygen and nitrogen.
(c)(i) Give one reason why bauxite is usually preferred as the ore for the extraction of aluminium.
(ii). List two main impurities. usually present in bauxite.
(iii) State the function of sodium hydroxide solution in the extraction of aluminium from its ore.
(iv) Explain briefly why it is difficult to extract aluminium by chemical reduction of aluminium oxide
(v) Write an equation for the reaction of aluminium oxide with aqueous sodium hydroxide.
(d) (i) The melting and boiling points of sodium chloride are 801 °C and 141.3 °C respectively. Explain briefly why sodium chloride does not conduct electricity at 25°C but does so between 801 °C and 1413 °C.
(ii) State the reason why sodium metal is stored under paraffin oil in the laboratory.
(e)(i) State what would be observed when aqueous sodium trioxocarbonate(IV) is added to a solution containing iron (III) ions
(ii) Write a balanced equation for the reaction in (e)(i).
View Discussion (0)WAEC 2016 THEORYThe electron configuration of26Fe3+ is
- A. [Ar]4s23d6
- B. [AR]4s23d3
- C. [AR]4s13d4
- D. [AR]4s03d5
Which of the following pairs of components have the same molecular mass? [ H = 1.0, C = 12.0, O = 16.0 ]
- A. Ethene and Ethyne
- B. Ethane and Ethene
- C. Carbon (ii) Oxide and Ethene
- D. Carbon (iv) Oxide and Ethyne