Question 10: Which one of the following properties is not generally exhibited by ionic compounds?
Explanation: Free ions are not available for conduction of electricity when ionic compound is in solid state.
Question 11: Which of the following metals exist in their native state in nature?
Explanation: These are non-reactive metals and hence are available in their native state in nature.
Question 12: Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
Explanation: Metals of high reactivity are refined by electrolytic refining.
Question 13: Silver articles become black on prolonged exposure to air. This is due to the formation of
Explanation: On prolonged exposure to air, silver reacts with hydrogen sulphide gas to make silver sulphide.
Question 14: Galvanisation is a method of protecting iron from rusting by coating with a thin layer of
Explanation: The process was named after an Italian scientist Luigi Galvani although Galvani had no involvement in zinc coating.
Question 15: Stainless steel is very useful material for our life. In stainless steel, iron is mixed with
Question 16: If copper is kept in open air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of
Explanation: When copper is kept in air for a long duration, it reacts with various gases in air to form copper hydroxide and copper carbonate. Copper acquires a green coating due to mixture of these compounds.
2Cu + H2O + CO2 + O2 → Cu(OH)2 + CuCO3
Question 17: Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?
Question 18: Which of the following metals are obtained by electrolysis of their chlorides in molten state?
Explanation: Metals of high reactivity are obtained by electrolytic refining. We know that sodium chloride is abundant in nature. This gives a clue for option d.
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