Metals and Non-metals

NCERT Exemplar Problems

MCQ Part 3

Question 19: Generally, non-metals are not lustrous. Which of the following nonmetal is lustrous?

1. Sulphur
2. Oxygen
3. Nitrogen
4. Iodine
   Answer: (d) Iodine

Question 20: Which one of the following four metals would be displaced from the solution of its salts by other three metals?

1. Mg
2. Ag
3. Zn
4. Cu
   Answer: (b) Ag

Explanation: In the reactivity series of metals, silver is at the bottom among given four metals.

Question 21: 2 mL each of concentrated HCl, HNO₃ and a mixture of concentrated HCl and concentrated HNO₃ in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be

1. Al
2. Au
3. Cu
4. Pt
   Answer: (b) Au

Explanation: A mixture of HCl and HNO₃ in 3:1 ratio is called Aqua regia, which dissolves gold and silver.

Question 22: An alloy is

1. an element
2. a compound
3. a homogeneous mixture
4. a heterogeneous mixture
   Answer: (c) A homogeneous mixture

Question 23: An electrolytic cell consists of

1. positively charged cathode
2. negatively charged anode
3. positively charged anode
4. negatively charged cathode

1. (i) and (ii)
2. (iii) and (iv)
3. (i) and (iii)
4. (ii) ad (iv)
   Answer: (b) (iii) and (iv)

Question 24: During electrolytic refining of zinc, it gets

1. deposited on cathode
2. deposited on anode
3. deposited on cathode as well as anode
4. remains in the solution
   Answer: (a) Deposited on cathode

Question 25: An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following

1. Mg
2. Na
3. P
4. Ca
   Answer: (b) Na

Question 26: Alloys are homogeneous mixtures of a metal with a metal or nonmetal. Which among the following alloys contain non-metal as one of its constituents?

1. Brass
2. Bronze
3. Amalgam
4. Steel
   Answer: (d) Steel

Explanation: Steel is a mixture of iron (metal) and carbon (non-metal). Brass is a mixture of copper and zinc. Bronze is a mixture of copper and tin. Amalgam is a mixture of mercury and any other metal.

Question 27: Which among the following statements is incorrect for magnesium metal?

1. It burns in oxygen with a dazzling white flame
2. It reacts with cold water to form magnesium oxide and evolves hydrogen gas
3. It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas
4. It reacts with steam to form magnesium hydroxide and evolves hydrogen gas
   Answer: (b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas