Metals and Non-metals
NCERT Exemplar Problems
MCQ Part 2
Question 10: Which one of the following properties is not generally exhibited by ionic compounds?
- Solubility in water
- Electrical conductivity in solid state
- High melting and boiling points
- Electrical conductivity in molten state
Answer: (b) Electrical conductivity in solid state
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?
- Cu
- Au
- Zn
- Ag
- (i) and (ii)
- (ii) and (iii)
- (ii) and (iv)
- (iii) and (iv)
Answer: (c) (ii) and (iv)
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?
- Au
- Cu
- Na
- K
- (i) and (ii)
- (i) and (iii)
- (ii) and (iii)
- (iii) and (iv)
Answer: (d) (iii) and (iv)
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
- Ag3N
- Ag2O
- Ag2S
- Ag2S and Ag3N
Answer: (c) Ag2S
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
- Gallium
- Aluminium
- Zinc
- Silver
Answer: (c) Zinc
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
- Ni and Cr
- Cu and Cr
- Ni and Cu
- Cu and Au
Answer: (a) Ni and Cr
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
- CuSO4
- CuCO3
- Cu(NO3)2
- CuO
Answer: (b) CuCO3
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?
- Na
- Fe
- Cr
- Hg
Answer: (d) Hg
Question 18: Which of the following metals are obtained by electrolysis of their chlorides in molten state?
- Na
- Ca
- Fe
- Cu
- (i) and (iv)
- (iii) and (iv)
- (i) and (iii)
- (i) and (ii)
Answer: (d) (i) and (ii)
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.