Class 10 Science

Metals and Non-metals NCERT In Text Questions

Part 2

Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4

Answer: When a reactive metal reacts with dilute hydrochloric acid, hydrogen gas is produced. The chemical equation for reaction between iron and dilute hydrochloric acid is as follows:

Fe + H2SO4 ⇨ FeSO4 + H2

At the end of this reaction, ferrous sulphate and hydrogen gas are formed.

What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.

Answer: Zinc displaces iron from iron (II) sulphate solution because zinc is more reactive than iron. This reaction can be shown by following equation:

Zn + FeSO4 ⇨ ZnSO4 + Fe

Write the electron-dot structures for sodium, oxygen and magnesium.

Answer: Electronic dot structure of Na(11)

electronic dot structure of sodium

Electronic dot structure of O (8):

electronic dot structure of oxygen

Electronic dot structure of Mg (12):

electronic dot structure of magnesium

Show the formation of Na2O and MgO by the transfer of electrons.

Answer: Electron dot structures of sodium oxide and magnesium oxide are as follows:

electronic dot structure sodium oxide
electronic dot structure magnesium oxide

What are the ions present in these compounds?

Answer: In both the compounds; oxide ions are present. Sodium ion is present in sodium oxide, while magnesium ion is present in magnesium oxide.

Why do ionic compounds have high melting points?

Answer: The force of attraction in ionic bonds is very strong and it is difficult to overcome that force. Hence, ionic compounds have high melting points.

Define the following terms.

(a) Mineral

Answer: A substance which naturally occurs in the earth’s crust and has a uniform composition is called mineral.

(b) Ore

Answer: A mineral from which a substance can be profitably extracted is called an ore.

(c) Gangue

Answer: The impurities present in an ore are called gangue.

Name two metals which are found in nature in the free-state.

Answer: Silver and gold

What chemical process is used for obtaining a metal from its oxide?

Answer: For obtaining a metal from its oxide, we need to use reduction. This process is carried out by heating the metal oxides; usually with a reducing agent.

Metallic oxides of zinc, magnesium and copper were heated one by one with zinc, magnesium and copper. In which cases will you find displacement reactions taking place?

Answer: Displacement reaction takes place only when zinc oxide is headed with magnesium. And No reaction takes place in other cases.

Which metals do not corrode easily?

Answer: Metals which are at the bottom of reactivity series do not corrode easily, e.g. copper, silver and gold.

What are alloys?

Answer: A homogenous mixture of two or more than two metals or a metal and a non-metal is called an alloy.