Waec 1990 Chemistry Past Questions And Answers
Which of the following reaction will not take place under normal conditions?
- A. Zn(s) + 2HCI2(aq) + H 2(g)
- B. Fe (s) + H 2SO4(aq) → FeSO4(aq) + H2(g)
- C. Cu (s) + 2HCI (aq) → CuCI 2(aq) + H2(g)
- D. Ca(s) + 2H Ca(OH)2(g)
(a) Arrange the first three members of the halogen family in their increasing order of electronegativity. Give the reason for your answer.
(b) State and explain what happens when chlorine reacts with starch iodide paper.
To make coloured glasses, small quantities of oxides of metals which form coloured silicates are often added to the reaction mixture consisting of Na2CO3 and SiO2. Such a metals is a?.
- A. pottasium
- B. barium
- C. zinc
- D. copper
(a) Give one reason why a collision between reactants may not produce new species.
(b) Explain, illustrating with appropriate equation(s), why an aqueous solution of aluminium chloride is acidic.
When a solid melts and consequently boils, there is
- A. a gradual increase in the average kinetic energy of the particles
- B. a sudden decrease in the kinetic energy of the particles
- C. no change in the average kinetic energy of the particles
- D. a rapid change in the nature of bonding of the components
(a) Write the electronic configuration of an element with atomic number 15, indicating the distribution of electrons in the energy sub-levels
(b) Give the formula and the colour of the complex formed between ammonia and copper (II) ions
A sample of orange juice is suspected to have been contaminated with a yellow dye. Which of the following methods can be used to detect the dye?
- A. Decantation
- B. Chromatography
- C. Distillation
- D. Filtration
A hydrocarbon X which decolorizes bromine water but has no action on ammoniacal silver trioxonitrate (V) solution was found to have a molar mass of 58 g mol\(^{-1}\)
(a) Deduce the molecular formula of X. (H = 1, C = 12)
(b) Write the structures of two isomers of X.
Nuclear reactions can be used in the following except
- A. gauging the thickness of objects
- B. making atomic bombs
- C. curing cancer
- D. purifying water
(a) Name the type of solid structure possessed by:
(i) diamond;
(ii) iodine;
(iii) sodium chloride.
(b) Give:
(i) one alloy of tin:
(ii) a common reducing agent which is a compound of tin.