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Dear students, prepare for chemistry class 10th chapter 8 long questions. These important long questions are carefully added to get you best preparation for your 10th class chemistry ch. 8 exams.
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Question: 1
State the law of mass action and derive the expression of equilibrium constant for general reaction?
Answer: 1

According to this law the rate at which a substance reacts is directly proportional to its active mass and the rate of a reaction is directly proportional to the product of the active masses of the reacting substances generally an active mass is considered as the molar concentration having units of mol dm-3 expressed as square brackets [ ] for example:

A+b____ Kf/kr C+D

The rate of kr the forward reaction * [Aa] [b]

= kf [A] [B]

Similarly: the rate of the reverse reaction

· [C] [D] = Kr [C] [D]

· The rate of forward = the rate of reverse reaction

· Kf [A] [B] Kr [C] [D]

· Kf/kr = [C] [D] ____ [A] [B]

· Where kc = kf/kr

· Kc is called equilibrium constant

· Kc= [C] [D]____[A] [B]

Question: 2
<div>What is meant by ph, give its uses?</div>
Answer: 2

Concentration of hydrogen ion [H+] in pure water is the basis for the ph sacle water is a week electrolyle because it ionizes very slightly into ions in a process called auto ionization

H2O______ H+ +OH

Kc = [H+] [OH-]/[H2O]

Kc [H2O] = [H+] [OH-]

Kc = [H+] [OH-] =1.0 *10-14 at 25° C

H+ = [OH-] or [H2] =1.0*10-14

[H+] = 1.0*10-14

Therefore: [H+] =1.0*10-7 at 25° C

Ph is the negative logarithem of molar concentration of the hydrogen ion:

Ph= - log [H+]

Ph= - log [H+]

Poh = -log [OH-]

Poh = - log ( 1.0*10.7)=7

Ph +poh =14

It is used to detemile acidic os basic nature of a solution it is used to produce medicines culture of a microbiological particular concentration of H+ ion it is used to prepare solutions of required concentration necessary for certain biological reaction.

Question: 3
Write macroscopic properties of dynamic equilibrium?
Answer: 3

An equilibrium is achievable only in a closed system at equilibrium state a reaction does not stop forward and reverse reaction keep on taking place at the same rate but in opposite direction at reactants and products do not change an equilibrium state is attainable from either way starting from reactants or from products , an equilibrium state can be disturbed and again achieved under the given condition of concentration pressure and temperature.

Question: 4
Write down physical properties of alkynes?
Answer: 4

Alkynes also form a series of compounds it first member I acetylene is a colorless gas with faint garlic odor,acetylene is slightly soluble in water but soluble in organic solven of acelone,elter etc,acelylene is slightly lighter than air.Alkynes are also flammable, they produce smokier flames them those of alkenes and alkenes.

Question: 5
Describe different methods for the preparation of alkanes?
Answer: 5

As we know alkanes from a series of homologous compounds so their methods of properties are similar although there are many methods of proparation but only two methods are discussed here.

Hydrogenation of alkenes and alkanes:

Hydrogenation means addition of molecular hydrogen in alkanes and alkanes, as we know alkanes and alkanes are unsaturated compound so they have to capacity to add up atom in them this reaction is carried out in the presence nickel catalyst at 250 ° C to 300 ° C

H2C = CH2+H2_______H3C-CH3

Similarly :

HC =CH +H2______H2C=CH2


Question: 6
Describe lewis concept of acids and bases?
Answer: 6

An acid is a substance which can accept a pair ofelectrons while a base is a substance which can donate a pair of electrons. While a base is a substance which can donate a pair of electrons:

The cations act as lewis acids or example a reaction between H+ and NH3 where H+ acts as an acid and ammonia as a base.

Lewis acids:

Molecules in which the central atom has incomplete octel for example:


Simple cations can act as lewis acids all cations act as lewis acids since they are deficient in electrons however,cations such as NA+,K+,CA2, ions.

Lewis base:

Neutral species having at least one lone pair of electrons, for ammonia ,amines,alcohols etc.


Negatively charge d species or anions for example choride, organic ,hudroxide ions etc act as lewis bases.

CN,CT,OH- etc.

Question: 7
<p class="MsoNormal">How is roasting carried out?</p>
Answer: 7

is process of heating concentrated are to high temperature in axcess of air following reaction occure in this:

2Cu FeS2______Cu2S+2FeS+SO

Question: 8
<p class="MsoNormal">How is ammonia prepared for the synthesis of urea?</p>
Answer: 8

Ammonia is prepared by the harber’s process one volume of nitrogen and three volumes of hydrogen is passed over iron catalyst at 450C and 200 at m pressure.

Question: 9
<p class="MsoNormal">Describe the difference between diesel oil and fuel oil?</p>
Answer: 9

Name : Deise oil , fuel oil

Composition: C13 to C15 , C15 to C18

Boiling range: 250 to 350 C 350 to 400C

Question: 10
<p class="MsoNormal">Which petroleum fraction is used in dry cleaning?</p>
Answer: 10

Petrolium ether is used in dry cleaning it is composed of C5 to C7

Question: 11
<p class="MsoNormal">Define gangue and metallurgy gangue?</p>
Answer: 11

The earthly and other impurities associated with the minerals are known as gangue.


The process of extraction of a metal in a pure state on a larger scale its one by physical or chemical means is called metallurgy.

Question: 12
<p class="MsoNormal">Describe forth floating process?</p>
Answer: 12

Forth floating process is based on the welting characteristic of the one and the gangue particles with oil and water.

Question: 13
<p class="MsoNormal">Describe the importance of urea?</p>
Answer: 13

Urea is nitrogenous fertilizers it has number of applications irragriculature.

Question: 14
<p class="MsoNormal">What process and involved in extraction of metal?</p>
Answer: 14

The metal is isolated from the concentration are by chemical reduction or electrolytic process.

Question: 15
<p class="MsoNormal">What is the deifference between slag and mattle?</p>
Answer: 15

Slag is mixture of metal silicates and phosphates while cuprous sulphide and fercus sulphide from a mixture (Cu2s.feS).

Question: 16
<p class="MsoNormal">Why is blister copper?</p>
Answer: 16

The dissolved gasses escape out forming blister on the surface of solid copper.

Question: 17
<p class="MsoNormal">How is CO2 prepared in solvays’s process?</p>
Answer: 17

It is formed by heating calcium carbonate :

CaCO3 (S)______ CaO(s)+CO2 (g)

Write two uses of kerosene oil?

Name: Kerosene oil

Composition C 10 to C 12

Boiling range: 170 to 250 C

Uses: It is used as domestic fuel and a special grade of it is used as jet fuel.

Question: 18
<p class="MsoNormal">Give the reaction fo fermentation of ammonia in the process in the form of equation?</p>
Answer: 18

It prepared by mixing one volume N2 and three volumes of H2 in the presence of ion catalyst at 450°C and 200 atom.

Question: 19
<p class="MsoNormal">How concentration of are is done?</p>
Answer: 19

The process of removal of gangue from the are is technically known as concentration and the purified are is called the concentrate.

Gravity separation

Forth flotation process

Electromagnetic separation

Question: 20
<p class="MsoNormal">Write function of fertilizers?</p>
Answer: 20

Fertilizers supplement essential nutrients in the soil needed by all plants for healthy , vigorous growth.

Question: 21
<p class="MsoNormal">Uses of fuel oil?</p>
Answer: 21

Fuel oil is used is ships and industries to heat boilers and furnaces.

Question: 22
<p class="MsoNormal">Write raw material for manufactural of urea?</p>
Answer: 22

The raw materials for the manufacturing of urea are

Ammonia (NH3) Carbon dioxide (o2) ammonia is prepared by the harber’s process .

Question: 23
<p class="MsoNormal">Why urea is important of compound?</p>
Answer: 23

It is used to make explosives .

It is used In auto mobile system to reduce the NO 2 pollutant in exhaut gasses.

Question: 24
<p class="MsoNormal">What is petroleum?</p>
Answer: 24

Petroleum is a complex mixture of hydrocarbons it is formed by decomposition of dead animals buried under the earth’s crust.

Question: 25
<p class="MsoNormal">What is principle of factional distillation?</p>
Answer: 25

The principle of fractional distillation depends upon separation of substances depending upon their boiling points.

Question: 26
<p class="MsoNormal">What is the difference between minerals and ores?</p>
Answer: 26

Minerals :

The solid natural materials founds beneath the earth surface which contains compounds of metals


Those minerals from which the metals are contracted commercially at a comparatively law cost with the minimum effort we call ones of the metal.

Question: 27
<p class="MsoNormal">Write two uses of petroleum gas?</p>
Answer: 27

As fuel as such in the from of LPG used of production of carbon black it is used to produce hydrogen gas needed to form ammonia NH3.

Question: 28
<p class="MsoNormal">How is petroleum extracted?</p>
Answer: 28

Petroleum I extracted by distillation holes into earth crust where oil is found.

Question: 29
<p class="MsoNormal">Write down the name of four fractions obtained by the fractional distillation of residual oil?</p><p class="MsoNormal"><br></p>
Answer: 29

The four fractions of residual


Paraffin war


Petroleum coke