12th Class Chemistry Chapter 7 Fundamental Principles of Organic Chemistry

Chemistry short QA

12th Class Chemistry Chapter 7 Fundamental Principles of Organic Chemistry Below

1.What is vital force theory?Who discarded this theory?
First of all it was though that the organic compounds were synthesized in the bodies of plants and animals in the presence of vital force which is present in plants and animals as well.This concept is called vital force theory.W.F Whole discarded it by preparing urea in the laboratory.
2.Which organic compound was first of all prepared in the laboratory?
In 1828 F.Wholer propared urea by heating ammonium xyanate in the laboratory.Urea is an organic compound present in the animal urine.
3.What is the modern definition of organic chemistry and which of the elements other than carbon and hydrogen may be present in organic compounds?
The study of the compounds containing carbon is called organic chermistry.The elements other than carbon and gydrogen present in various organic compounds are oxygen sulphur nitrogen phosphorus halogens and a few metals.
4.Mention those compounds of carbon which are not organic in nature?
The following comounds have caron in them but they are not though to be  organic in nature.These compounds are CO.CO2,CS2,HCN,metal cyanides metal carbides carbonates and bicarbonates of metals.
5.Catenation is the property which makes carbon different from other elements of the periodic table.justify it?
Carbon has property to link with other atoms of carbon.This property of self-linkage is called catenation.Due to this property a separats branch of chrmistry called organic chemistry is developed.
6.How the phenmenon isomerism makes the organic compounds greater in number?
The existance of more than one structures and having different physical and chemical properties with the same molecular formula is called isomerism.Butane has two isomers.Pentane has three and hexane has five.In this way,the number of possible molecules increases.
7.Oranic compounds mostly give slow reactions as compared to inorganic compounds.Give resons?
Organic compounds are mostly covalent in nature and insoluble in water.Their polarity is not so much pronouced so the reactions are slow.
8.Organic compiunds are mostly non-ionic in character.Give reasons?
Organic compounds are made up of such elements which have small differences of electronegativities.The bonds are very close to the covalent character and hence non-ionic.
9.Which are most important solvents and are used to dissolve organic compounds?
The important solvents are ether methanol ehanol, benzene carbon tetrachloride chlorform acetone and petroleum ether.
10.How the organic compounds are closely associated with the human body?
The substances like our food clothing medicines vitamins antibiotics insecticides harmones pigments paper ink perfumes soaps detergents petroleum and plastics etc.are needed by the human beings and they are all organic substances .
11.Coal is one of the major sources of organic compounds.How do you justify it?
Coal has plant origin and one of its fractions is coal tar.A large number of organic commpounds are present in coal tar.More than 215 organic compoounds can be extracted from four fractions of coal tar.
12.Indicate five fractions which are obrained from destructive distillation of coal?
When coal undergoes destructive distillation between 1000- 1400 ᵒC the following five fractions are obtained.
Crude coal,       Ammonical liquor,        Coal tar ,    Coke,    Gas carbon
13.What iws coal tar?Give its fractions?
coal tar is one of the fractions obtained from destructive distillatin of coal.When it undergoes fractional distillation four fractions are obtained having aooroximately 215 organic compounds.
Coal Tar
Light oil,         Middle oil,                     Heavy oil            Anthracite oil.
(150-200ᵒC)      (200-250ᵒC)                (250-300ᵒC)       (300-350ᵒC)
14.What is the composition of natural gas?
Natural gas is consisted of 80-95% methane.It has small amounts of C2H6 C3H8 and C4H10.It also contains CO2 H2S and nitrogen gas.
15.Give important uses of natural gas?
Natural gas is used as a fuel to produce carbon black and acts as a raw material for the manfacture of urea.It is also used for power generation in cement and fertilizer industries.
16.What is petroleum?Give its origin?
Petroleum is naturally occuring brown or greenich black viscous oily liquid which is obrained from the Earth’s crust.It has biological origin and is formed due to decay and decomposition of marine animals.
17.Name the fractions which are obtained by fractional distillation of petroleum?
When petroleum undergoes fractional distillation various fractions are natural gas petroleum ether light naphtha gasoline kerosene oil diesel oil lubrication oil and asphalt.
18.What is an oil refinery?Mention oil refineries in Pakistan?
The industries which purify petroleum and separate different components are called oil refineries.In Pakistan we have Attack oil refinery at Rawalpindi,Pak-Arab refinery at Multan and two refineries at Karachi.
19.What is cracking of petroleum?Who do we need cracking of petroleum?
The process of decomposition of less volatile higher hydrocarbons into more volatile lower hydrocarbons with the applications of heat and catalyst is called cracking.Fractional distillation of petroleum only gives 20% gasoline.The rest of the deficiency is compensated by cracking.Approximately 50% of gasoline is now prepared by this method.
20.Give the products by the cracking of n-butane?
21.What is thermal cracking?
That cracking which is carried out by the application of heat and pressure is called thermal cracking.In liquid phase the temperature of 475-530ᵒC is maintained with a pressure of 7-70 atm.In vapour phase cracking the temperature is 600ᵒC and the pressure is 3.5 – 10.5 atm.
22.What is catalytic cracking?
The type of cracking of hydrocarbons which is done in the presence  fo catalysts like siO2 and AI2O3 is called catalytic cracking.
23.What is steam cracking?
Higher hydrocarbons are converted to vapour and mixed with steam.This mixture is heated for a short time to about 900ᵒC and then cooled rapidly.This cracking gives us lower unsaturated hyrocarbons.
24.What do you mean by knocking of petroleum?
Knocking is the metallic sound during the combustion of gasoline in internal combustion engines.The gasoline having lower octane number produces knocking.
25.How do you define octane number and how it can be improved?
Octane number is the % age by volume of iso-octane and n-heptane which has the same knocking property as the fuel being tested under the similar experimental conditions in the special test engine.If we have greater % age of iso-octance the oxtane number is improved.
26.What is reforming of petroleum?
27.Give at least five compounds which are homocyclic and are carbocyclics but are not aromatic?
28.Give four example of aromatic heterocyclic compounds and two examples of homocyclic aromatic?
29.What are aromatic hydrocarbons?Give two examples?
30.What is meant by functional group?Name and represent two functional groups containing oxygen?
31.Give characteristics of homologous series?
The members of homologous series contain same elements and same functional group.They have the same general formula and the members differ by – CH- units.Their properties and preparations are identical and their physical properties change gradually.
32.Draw the structure of CH4 and CCI4,indicating the sp3- hybridization of central carbon atom?
33.Draw the structure of C2H4 and indicate the bond lengths and bond angles?
34.Draw the structure of C2H2 and indicate the bond length and bond angles?
35.Why all the bond angles of propane are not equal?
36.What is isomerism?Give the name of four structural isomerism?
That phenomenon in which two or more than two compound have the same molecular formulae but differ at least in some physical or chemical properties is called isomerism. There are five types of structural isomerisms: i) Chain isomeris or skeletal isomerism. ii) Positional isomerism iii). Functional group isomerism. iv) Metamerism. v) Tautomerism
37.Give the examples of chain isomers of an alkynes having three chain isomers?
38.Give examples of positional isomers in alkenes and alkynes?
39.Write isomers of C4H10?

It has isomers which are chain isomers of each other.
CH3 CH2– CH2– CH3.          CH3.CH – CH3.
n-Butane                           2-Methyl propane

40.Give two example of functional group isomers?
a) CH3 – O-CH3         CH3– CH2-OH are functional group.
Dimethyl ether              Ethyl alcohol    isomers of each other
b). CH3-CH2-CHO            CH3– C-CH3 are functional group
Propanal                    Propanone    isomers of each other.
41.What is metamerism?Give one example?
Those structural in which a polyvalent atom is attached with different types of alkyl groups. CH3 CH2OCH2 CH3.and CH3 OCH2 CH2  CH3. Are metamers of each other.
42.Butene does not show geometrical isomerism but 2-Butene does.Give reasons?
43.2-Butyne does not show geometrical isomerism but 2-butene does.Give reasons?
44.Why is restricted rotation necessary to show the geometrical isomerism?
The bonds are always rotating so a molecule can attain any conformation.If there is a double bond then the presence of bond does not allow the sigma bond to rotate and the rotation is hindered.In this way cis and trans geometrical isomers can exist.
45.How the resticted rotation of the cyclic compounds gives birth to the geometrical isomerism?
46.Define tantomerism with an example?
It is that type of isomerism in which an atom is transferred from one part of the molecule to the other within same molecule.
O                                              OH
CH3 –  C –  CH3                                CH2=C – CH3
Acetone(keto form)                        (Enolic form)
H-atom has transferred from carbon to oxygen atom.This is called keto-enol tautomeris.
47.A π bond is weaker than a o-bond.justify it?
π bond are formed by parallel overlapping of p-orbitals.Two electrons give two lobs above and below the o-bond.It is weaker bond and less energy is required to break it.Its electronic cloud is more diffused as compared to electrons of o-bond.
48.What is carbonization?
It involves heating of coal at about 1270 K in the absence of air.It is also called destructive distillation of coal or pyrolysis.
49.Give the boiling point range(ᵒC) and composition of (a) kerosene (b) naphtha?
a)Kerosene oil has B.P range of 175-325 ᵒC and its hydroxarbons vary form C8H18 .to C14H30.
b) Naphtha obtained from distillation of petroleum has a number of confusing names which are unscientific  and chemically erroneous.These names are petroleum ether  petroleum spirits mineral oil,mineral spirits.Their M.P may be between 50-60ᵒC and has compounds above C23H48.
50.Classify open chain compounds with examples?
There are two types of such compounds (i) Straight chain                (ii) Branched chain.
CH3. CH2– CH2– CH3. n-butane(st.chain)
CH3– CH- CH3.            Iso-butane(branched chain)

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