NCERT Class X Science Class: Chapter –3. Metals and Nonmetals– Part-10

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Question 57:

An element forms an oxide which is acidic in nature. Identify A as a metal or non-metal.

Answer:

Oxides of non-metals are acidic in nature while those of metals are basic. As the element A forms an acidic oxide, therefore, A must be a non-metal. Also it should have charge, i.e., it should have 3 valence electrons. Therefore, A is boron, (electronic configuration is 2, 3) and its oxide is

Since an oxide of element is acidic in nature, therefore, A will be a non-metal.

Question 58:

A solution of was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

Answer:

The higher equation of iron displaces copper from and it is being consumed then holes appears on the pot.

This should come with metal displace and lower order metal do it so.

On the other hand, the Cu changes to Cu metal and consider it accordingly.

It displaces from and iron is being consumed then holes.

is more reactive as compared to . Therefore, Fe displaces from and forms

Long Answer Questions

Question 59:

A non-metal A which is the largest constituent of air, when heated with ratio in the presence of catalyst gives a gas B. On heating with it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.

  1. Identify A, B, C and D

  2. To which group of periodic table does this non-metal belong?

Answer:

For (a):

Non-metal A is nitrogen gas since, the percentage of in air is largest, i.e., 78%. When is heated with in ratio in presence of as catalyst, it forms ammonia Thus, B is ammonia gas. Gas B, when heated with , it forms nitric oxide . NO further gets oxidized to by of the air. Thus, C is (nitrogen dioxide).

When this oxide is passed into water in the presence of air it gives nitric acid which acts as a strong oxidising agent. Thus, Dis nitric acid

For (b):

The non-metal belongs to group 15 or VA because N has valence electrons (electronic configuration is

Question 60:

Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Answer:

Firstly the sulphide ore is changed into metal oxide ore by roasting. secondly the metal oxide is heated and we get pure metal.

Sulphide ore of low reactivity metal pure metal

Sulphide ore of medium reactivity metal

Question 61:

Explain the following

  1. Reactivity of decreases if it is dipped in

  2. Carbon cannot reduce the oxides of

  3. is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state

  4. Iron articles are galvanized.

  5. Metals like are never found in their free state in nature.

Answer:

A) When aluminium is dipped in nitric acid a layer of aluminium oxide is formed on the metal. This happens because nitric acid is a strong oxidizing agent. The layer of aluminium oxide prevents further reaction of aluminium. Due to this, the reactivity of aluminium decreases.

B) Sodium and magnesium have higher affinity towards oxygen than towards carbon because these are highly reactive metals. Hence, carbon cannot reduce the oxides of Na or Mg.

C) Ionic compounds do not conduct electricity in solid state but they conduct electricity in aqueous solution and in molten state. Hence, this property is shown by sodium chloride.

D) Iron articles are galvanized to prevent rusting of iron. After galvanization, the layer of zinc works as protective layer.

E) Metals; like Na, K, Ca and Mg are highly reactive metals and hence they are not found in their free state in nature