11th Class Chemistry Chapter ten Short Questions with Answers Solved

Question: 1

A porous plate or a salt bridge is not required in lead storage cell.Give reason?

Answer: 1

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A porous plate or salt bridge is used in those cells where two different electrolytes are used and are required to keep separate.In case of lead storage cell, only dil.H₂SO_{4 is used as an electrolyte. Hence, no separation is required by porous plate or salt bridge.}

Question: 2

Describe the relative chemical reactivity of metals?

Answer: 2

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Metals react by forming their positive ions.If the value of standard reduction potential is greater, the tendency to form positive ions is smaller and therefore less reactivity.It means the elements with greater reduction potential are least reactive where as the elements with smaller reduction potential are more reactive.

Question: 3

Write the importance of standard hydrogen electrode?

Answer: 3

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Standard hydrogen electrode (SHE) is used to determine the electrode potential of other electrode.It is used as reference electrode and its value is 0.0 volt. From SHE we drive electrochemical series.

Question: 4

Differentiate between electrolytic cell and voltaic cell.

Answer: 4

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Electrolytic Cell:

The electrochemical cell in which electrical energy is converted into chemical energy is called Electrolytic cell.
In this cell, non-spontaneous reaction occurs.
Electric current is used to drive the non-spontaneous oxidation reduction reaction.
Electrolysis takes place in this cell.

Example: Down's cell, Nelson"s cell

Question: 5

Give four rules for assigning of oxidation number?

Answer: 5

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The oxidation number of free elements is zero.For example H, Mg, Na.as charge on the ion.
Oxidation number of hydrogen in all its compounds is +1 except metal hydride where it is -1
In neutral molecules, the algebric sum of oxidation number of all the elements is zero.

Question: 6

Differentiate between electrolysis and electrolytic conduction?

Answer: 6

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Electrolysis; The process in which electricity is used to carry out a non-spontaneous redox reaction is called electrolysis.

Electrolytic Conduction: The conduction of electricity carried out by ions present in fused or aqueous solution of an electrolyte is called electrolytic conduction.

Question: 7

Na and K can displace hydrogen from acids but See you cannot.Justify it?

Answer: 7

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Greater the value of standard reduction potential of a metal , lesser is its tendency to lose electrons to form metal ions and so weaker is its tendency to displace H₂ From acids.For example, metal like Au, Pt, Ag and See you which have sufficiently high positive values of reduction potentials, do not liberate hydrogen from acids.while, metal like Na,Ma and K which are close to the top of the series and have very low reduction potentials, liberate hydrogen gas, when they react with acids.

Question: 8

Differentiate between electrolytic and voltaic cells?

Answer: 8

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Electrolytic cell:

A cell in which electrical energy is converted into chemical energy.
Non-spontaneous redox reaction takes place here.
Example: Down's cell

Question: 9

Define standard electrode potential?

Answer: 9

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Standard electrode potential: The potential setup when an electrode is in contact with one molar solution of its own ions at 298 k is called standard electrode potential.It is denoted by E°

Question: 10

Define Electrochemistry?

Answer: 10

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It is the branch of chemistry which deals with the conversion of electrical energy into chemical energy in electrolytic cells as well as the conversion of chemical energy into electrical energy in galvanic or voltaic cell,

Question: 11

Give some advantages of fuel cells?

Answer: 11

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These cell run continuously as long as reactants are available.
Theses are light, portable and source of electricity.
These are very efficient.They convert about 75% of fuels energy into electricity.

Question: 12

What is the difference between metallic conduction and electrolytic conduction?

Answer: 12

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Electrolytic Conduction: The conduction of electricity carried out by ions present is fused or in an aqueous solution of an electrolyte is called electrolytic conduction.

Metallic Conduction: The conduction of electricity through a metal due to free electrons is called metallic conduction.

Question: 13

How relative chemical reactivity of metals is studied with the help of electrochemical series.

Answer: 13

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The value of the reduction potential of a metal or a non metal tells us the tendency to lose electrons and act a reducing agent.It also gives the information about the tendency of a specie to gain electrons and act as oxidizing agent. Greater the value of standard reduction potential of a given specie, greater is its tendency to accept electrons to undergo reduction and hence to act as oxidizing agent.

Question: 14

Define electrolytic cell.Give example?

Answer: 14

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Electrolytic cell: A cell is which electric current is used to carry out a non-spontaneous reaction is called electrolytic cell.

Example:

Down's cell
Nelson cell

Question: 15

Zn can displace iron from its solution, how?

Answer: 15

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Zn is a stronger reducing agent having standard reduction potential as (0.76) than iron which has standard reduction potential as (0.44).So Zn can displace iron from its solution.

Question: 16

Differentiate between a cell and battery?

Answer: 16

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Cell: The arrangement in which electrical energy is converted into chemical energy or chemical energy is converted into electrical energy is called cell.

Battery: The combination of two or more cells is called battery.

Question: 17

Na and K can displace hydrogen from acids but Pt, Pd and See you cannot.Comment on it?

Answer: 17

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Greater the value of standard reduction potential , lesser is the ability to loose electrons.Hence its reactivity is less. Na and K are highly reactive metals.They can easily displace hydrogen from acid whereas Pt, Pd See you are least reactive metal.Therefore cannot easily displace hydrogen.

Question: 18

How anodized aluminum is produced and why it can absorb dyes?

Answer: 18

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Anodized aluminum is prepared by making it an anode in an electrolytic cell containing sulphuric acid or chromic acid, which coats a thin layer of oxide on it. The aluminum oxide layer resist attack by corrosive agents.The freshly anodized aluminum is hydrated and can absorb dyes.

Question: 19

What is Anodized Aluminum?

Answer: 19

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When a thin layer of oxide is formed over the surface of aluminium metal it is called anodized aluminium.Anodized aluminium is prepared by making it anode in an electrolyte cell containing sulphuric acid or chromic acid, Which costs a thin layer of oxide on it.Aluminium oxide layer resist the attack by corrosive agents.

Question: 20

Explain the function of salt bridge?

Answer: 20

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Function of salt Bridge: A salt bridge performs following functions:

It brings electrical contact between two half cells.
It maintains electrical neutrality of two solutions.

Question: 21

What is the difference between primary and secondary cells?

Answer: 21

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Primary Cells: The cells which cannot be recharged are called primary cells.e.g Dry cells.

Secondary Cells: The cells which can be recharged are called secondary cells.e.g. Fuel cells.

Question: 22

Zn can displace hydrogen from dilute acid solution but copper cannot.

Justify the statement?

Answer: 22

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Question: 23

Define the electrochemical serie?

Answer: 23

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The elements are arranged in the order of their standard electrode potentials on the hydrogen scale, the resulting list is known as electrochemical series. This list have been prepared by comparison with standard hydrogen electrode (SHE).In this list, elements above SHE have negative reduction potential while below have positive reduction potential .

Question: 24

What is meant by electromotive force (emf) of cell?

Answer: 24

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Electromotive force (emf): The electric current obtained from galvanic cell is a result of electrons being pushed or forced from the negative electrode, throughout an external wire, to positive electrode. The force with which these electrons move throughout the wire is called electromotive force. It is also called potential . It measured in volts.

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11th Class Chapter ten Chemistry Short Questions

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