Class 10 Science

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?

  1. Solubility in water
  2. Electrical conductivity in solid state
  3. High melting and boiling points
  4. 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?

  1. Cu
  2. Au
  3. Zn
  4. Ag
  1. (i) and (ii)
  2. (ii) and (iii)
  3. (ii) and (iv)
  4. (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?

  1. Au
  2. Cu
  3. Na
  4. K
  1. (i) and (ii)
  2. (i) and (iii)
  3. (ii) and (iii)
  4. (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

  1. Ag3N
  2. Ag2O
  3. Ag2S
  4. 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

  1. Gallium
  2. Aluminium
  3. Zinc
  4. 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

  1. Ni and Cr
  2. Cu and Cr
  3. Ni and Cu
  4. 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

  1. CuSO4
  2. CuCO3
  3. Cu(NO3)2
  4. 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?

  1. Na
  2. Fe
  3. Cr
  4. Hg
    Answer: (d) Hg

Question 18: Which of the following metals are obtained by electrolysis of their chlorides in molten state?

  1. Na
  2. Ca
  3. Fe
  4. Cu
  1. (i) and (iv)
  2. (iii) and (iv)
  3. (i) and (iii)
  4. (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.