21. The number of Hydrogen ions in 1.0dm3dm3 of 0.02moldm−3moldm−3 tetraoxosulphate(VI) acid is [NA=6.02×1023][NA=6.02×1023]
- A. 1.2×10221.2×1022
- B. 1.2×10231.2×1023
- C. 2.4×10222.4×1022
- D. 2.4×1023
22. The most suitable substance for putting out petrol fire is
- A. water
- B. carbon(IV) oxide
- C. fire blanket
- D. sand
23. The following factors would contribute to environmental pollution except
- A. production of ammonia
- B. manufacture of cement
- C. photosynthesis
- D. combustion
24. The position of equilibrium in a reversible reaction is affected by
- A. particle size of the reactants
- B. vigorous stirring of the reaction mixture
- C. presence of a catalyst
- D. change in concentration of the reactants
25. 
The diagram above illustrates a conical flask containing water and ice. Which of the following is correct about the diagram?
- A. The water is at lower temperature than the ice
- B. Energy is absorbed when the ice changes to water
- C. Energy is released when the ice changes to water
- D. The water molecules vibrate about a fixed point
26. Which of the following statements best explains the difference between a gas and a vapour?
- A. Unlike gases, vapours are liquids at room temperature
- B. Unlike gases, vapour can easily be condensed into liquids
- C. Unlike gases, vapour is readily converted into solids
- D. Vapours are generally denser than gases
27. Consider the following reaction equation: 2HCl+Ca(OH)2→CaCl2+H2O2HCl+Ca(OH)2→CaCl2+H2O. What is the volume of 0.1moldm−3moldm−3 HCl that would completely neutralize 25cm3cm3 of 0.3moldm−3moldm−3 Ca(OH)22?
- A. 150cm3cm3
- B. 75cm3cm3
- C. 30cm3cm3
- D. 25cm3
28.
CuCu and HNO3HNO3 are not suitable for preparing hydrogen gas because of their
- A. reactivity and oxidation respectively
- B. conductivity and corrosiveness respectively
- C. melting point and reduction respectively
- D. electronegativity and solubility respectively
29. Which of the following CANNOT be an empirical formula?
- A. CHCH
- B. CH2CH2
- C. P2O5P2O5
- D. N2O4
30. One of the criteria for confirming the purity of benzene is to determine its
- A. heat capacity
- B. boiling point
- C. mass
- D. colour
