NCERT Class 10 Chapter 5 Metals and Nonmetals CBSE Board Sample Problems Long Answer

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Question

State three reason:

a) Sulphur is a non-metal

b) Magnesium ¡s a metal

Solution

a) a) Sulphur is a poor conductor of electricity.

b) Sulphur is brittle.

c) It reacts with oxygen to form sulphur dioxide which forms acidic solution in water

b) a)Magnesium is a good conductor of electricity.

b) It is malleable and ductile.

c) It forms basic oxide when it reacts with oxygen.

Question

Give reason for the following:

a) Titanium is a strategic metal.

b) Non-metals do not form positively charged ions.

c) Aluminium is a reactive metal but does not corrode easily.

Solution

a) Due to its unique property that it is light in weight, but at the same time it is stronger than other metals, it is used in space science projects, jet engines, high grade steel etc. therefore, it is called strategic metal.

b) Non-metals do not loose electrons easily to form positive ions.

c) Aluminium reacts with oxygen in air and forms a protective oxide layer and prevents its corrosion.

Question

Write any three properties of ionic compounds?

Solution

i) Ionic compounds have strong melting and boiling point because they have oppositely charged ions which are held together by strong electrostatic force, so a lot of heat energy is required to break the bond.

ii) Ionic compounds are usually a crystalline solids because their oppositely charged ions attract one another strongly and form a regular crystalline structure.

iii) Ionic compounds are usually soluble in water but insoluble in organic solvents like ether, benzene alcohol, kerosene etc.

Question

Two Ores on Heating. A gives. Whereas ore B gives. Explain the processes with help of balanced chemical equation, which is used to convert ores A and B into their oxide ores with an example.

Solution

Ore A ¡s Carbonate Ore.

The process involved ¡n converting ores

Calcination: The Carbonate ore is heated strongly in absence of air.

Roasting: The sulphide ore is heated strongly ¡n presence of excess of air, this is known as roasting.

Question

(a) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding potassium metal to water catches fire. Explain why?

(b) Name a metal for each case:

(i) It displaces hydrogen gas from nitric acid.

(ii) It does not react with any physical state of water.

(iii) It does not react with cold as well as hot water but reacts with steam.

Solution

(a) In both cases, the gas evolved is . When calcium reacts with water the heat evolved is not sufficient for hydrogen to catch fire. On the other hand, potassium reacts with water violently and lot of heat is evolved which is sufficient for hydrogen to catch fire.

(b) (i) Zinc

(ii) Copper

(iii) Aluminium

Question

What is meant by refining of metals? Name the most widely used method of refining impure metals produced by various reduction processes. Describe with the help of a labeled diagram how this method may be used for refining of copper.

Solution

Process of obtaining pure metal from its impure form is called refining of metals.

The most widely used method for refining impure metals is electrolytic refining.

Electrolytic refining of copper: In electrolytic refining of copper, electrolyte is a solution of acidified copper sulphate. Anode is made up of impure copper. Cathode is made up of a strip of pure copper metal. On passing current through the electrolyte, pure copper metal from the anode dissolves into the electrolyte

i.e., acidified copper sulphate. Cu (Impure copper)

At cathode: An equivalent amount of pure metal from the electrolyte is deposited on the cathode. (Pure copper)

The soluble impurities go into the solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.

Electrolylic refining of copper

Electrolylic Refining of Copper

Question

What is thermite reaction? Give its one use.

Solution

A chemical reaction in which more reactive metal acts as a reducing agent and the reaction is highly exothermic hence releases large amount of heat is called thermite reaction. The metal produced in such reactions is in molten state which is used to join railway tracks or cracked machine parts.

Question

a) Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.

b) In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Solution

a) Extraction of pure metals from Carbonate ores-i

¡) Concentration of ore Gangue ¡s removed from the ore.

ii) Calcination

The carbonate ore ¡s heated strongly in absence of air

iii) Reduction by carbon or more reactive metal

b) Electrolytic refining of metal

M- anode - impure metal

Cathode - pure metal

Electrolyte — acidified metal salt

Question

a) Write chemical equations for the following reactions: Cinnabar is heated in the presence of air.

Manganese di oxide is heated with aluminium powder.

b) What is Solder? Why it is used for welding electrical wires?

c) How do the properties of iron change when small quantity of carbon is mixed with it?

Solution

i)

ii)

b) Solder is an alloy of Lead and Tin. It has low melting point.

c) Iron becomes hard and strong when small quantity of carbon is mixed with it.

Question

A metal X present in rock salt is highly reactive and it is stored under kerosene to prevent it from catching fire. ft. exists in nature as XCI. Identify the metal ‘X’. How can this metal be extracted from its chloride ore. Write chemical equations to explain your answer?

How is calcination different from roasting?

Solution

1 .This metal is Sodium. This metal is extracted from sodium chloride by electrolytic reduction of molten sodium chloride. The metal gets deposited at negatively charged electrode or cathode whereas chlorine is liberated at positively charged electrode or anode the reactions involved are:

At cathode:

At anode:

2. Calcination: Heating ore in the absence of air. ()

Roasting: Heating ore in the presence of air.

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