Chemistry Past Questions And Answers
Due to the unstable nature of ethyne, it is stored by dissolving in
- A) ethane-1,2-diol
- B) propanol
- C) ethanoic acid
- D) propanone
Steam changes the colour of anhydrous cobalt (II) chloride from
- A. blue to pink
- B. white to red
- C. white to green
- D. blue to white
Waste plastics accumulate in the soil and pollute the environment because plastic materials are
- A. insoluble in water
- B. non -biodegradable
- C. easily affected by heat
- D. inflammable
The group IA metals are not found free in nature because they
- A. are very reactive and unstable
- B. are malleable and ductile
- C. have high melting and boiling point
- D. conduct heat and electricity
The reactivity of fluorine is high because of
- A. its high electronegativity
- B. the small size of the fluorine atom
- C. the availability of d-orbitals
- D. the strong F-F bond
When starch undergoes complete enzyme-catalysed hydrolysis, the resulting product is
- A) glucose
- B) maltose
- C) sucrose
- D) fructose
A mixture of sand, ammonium chloride and sodium chloride is best separated by?
- A. sublimation followed by addition of water and filteration
- B. sublimation followed by addition of water and evaporation
- C. addition of water followed by filtration and sublimation
- D. addition of water followed by crystallization and sublimation
Equal amounts of marble chips are reacted separately with 100cm3 of hydrochloric acid of different concentrations. If all the marble chips reacted; which of the following remained the same in each case?
- A. Average rate of evoluton of gas
- B. Total mass of gas evolved during the reaction
- C. Time taken for the reaction to reach completion
- D. Initial reaction rates
(a)(i) List three factors which affect the discharge of ions during electrolysis
(ii) Describe in outline, the purification of copper by electrolysis.
(b) the following data were collected in an experiment on electrolysis:
| Current flowing(amps) | Time of current flow (secs) | Quantity of electricity (coulombs) | Mass of metal M deposited (gram) |
0.20 0.20 0.20 0.20 | 900 1800 2700 3600 | 0.06 0.12 0.18 0.24 |
(i) Copy and complete the table above calculating the quantity of electricity passed in each case
(ii) Plot a graph of the mass of M deposited against the quantity of electricity passed.
(iii) From the graph, determine the mass of M that was deposited by the same current passing for 20 minutes.
(iv) From the shape of the graph, which of the laws of electrolysis does the experiment verify?
View Discussion (0)WAEC 1996 THEORYThe primary component of natural gas
- A. ethane
- B. methane
- C. butane
- D. propane