Chemistry Model Test Questions X Chapter # 3 Organic Chemistry
Short Questions
Q1.Define following:
Organic chemistry, catenation, functional group, homologous series,
alkyl radical, vital force theory, condensed formula, saturated hydrocarbons,
unsaturated hydrocarbons, alicyclic compounds, aromatic compounds, cyclic
compounds
Q2. What
is catenation? Give any two examples of catenation of carbon atoms.
Q3. Define structural
formula. Write down the structural formula, condensed formula and dot and cross
formulae of n-butane and isobutane.
Q4. What
is homologous series? Name the some common homologous series with examples. Write
down the general characteristics of homologous series.
Q5. Define
the alkyl radicals with suitable examples. How are alkyl radicals formed? Explain
different radicals of butane.
Q6. What
is the difference between n-propyl and isopropyl radicals? Explain with
structure.
Q7.Differentiate
between saturated and unsaturated hydrocarbons
Q8.Identify the functional groups in the following compounds:
(a) CH3CHO (Aldehydic group)
(b) CH3CH2CH2OH (primary alcoholic group
(c) CH3COCH3 (ketonic carbonyl group)
(d) CH3COOH (carboxylic group)
(e) CH2=CHCH3 (double bond)
Q9. Name the alkenes and alkynes having the following formula
(i) C2H4 (ethene)
(ii) C3H4 (propyne)
(iii) C2H6 (ethane)
(iv) C6H12 (hexene or cylcohexane)
(v) C5H8 (pentyne)
(vi) C8H16 (Octene)
(vii) C7H12 (Heptane)
(viii) C6H10 (Hexyne)
Q10. Define
functional group. Write different functional groups which contain carbon,
hydrogen and oxygen.
Q11. What is an ester
group? Write down the formula of methyl acetate and ethyl acetate.
Q12.What is an ether
linkage? Give its general formula. Draw the structural formulae of any two
members of this family.
Q13.Differentiate
between aldehydic and ketonic groups? Give structural formulae of first member
of each family?
Q14. What are alkyl
halides? Give the name and formula of its functional group. Write down names,
functional group, class formula and
examples of three types of alkyl halides.
Q15. What are alcohols?
Give the name and formula of its functional group. Write down names, functional
group, class formula and
examples of three types of alcohols.
Q16. Write a detailed
note on functional groups of alkenes and alkynes.
Q17.What are amines?
Explain the different types of amines giving an example of each type.
Q18. What are
heterocyclic compounds? Give two examples.
Q19. Why are benzene and
other homologous compounds of benzene called aromatic compounds?
Q20. How is coal formed?
What are the different types of coal? Which is the best quality of coal?
Q21. What is natural
gas? Give its composition. Write down the importance of natural gas?
Q22. Encircle the functional groups in the following compounds. Also give the names of the functional groups?
Detailed Questions
Q1. Give
the important characteristic of organic compounds.
Q2. What
do you mean by diversity and magnitude of organic compounds? Give at least 4 reasons.
Q3. What
are the main sources of organic compounds? Mention with special reference of
coal, petroleum and natural gas.
Q4. Describe
the uses of organic compounds.
Q5. Define
nomenclature and describe IUPAC nomenclature rules for alkynes and alkanes.
Give IUPAC
names of Following Organic Compounds
Multiple
Choice Questions (MCQs) of Organic Chemistry from Text Book
1.The branch of chemistry which deals with the hydrocarbons and their derivatives is known as
(a) Organic chemistry
(b) Inorganic chemistry
(c) Biochemistry
(d) Physical chemistry
2.The general formula of alkanes is
(a) CnH2n
(b) CnH2n+1
(c) CnH2n+2
(d) CnH2n–2
3. Which of the following is an alcohol?
(a) CH3CHO
(b) CH3CH2OCH3
(c) CH3OH
(d) HCOOH
4.Which of the following is saturated hydrocarbon?
(a) CH3CH=CH2
(b) CH3CH2CH3
(c) CH3C≡CH
(d) CH2=CH–C≡CH
5. The prefix “hept” stands for the …………carbon atoms.
(a) 2
(b) 5
(c) 7
(d) 9
6. The functional group – COOH is used for
(a) Alkynes
(b) Alcohols
(c) Phenols
(d) Carboxylic acids
7. Polyethene is
(a) Oil
(b) paper
(c) plastic
(d) wood
8. Acetic acid is obtained from
(a) Banana
(b) Dates
(c) Garlic
(d) Vinegar
9.Alkenes
(a) show same general formula as alkynes
(b) have carbon-carbon triple bond
(c) have carbon-carbon double bond
(d) are saturated hydrocarbons
10. CH3–CH2– is ………… radical.
(a) Methyl
(b) Ethyl
(c) n-propyl
(d) iso-propyl
Answers of Short Questions
Q1. Define following:
Organic chemistry, catenation, functional group, homologous series,
alkyl radical, vital force theory, condensed formula, saturated hydrocarbons,
unsaturated hydrocarbons, alicyclic compounds, aromatic compounds, cyclic
compounds
Answer
Organic Chemistry
The study of covalent
compounds of carbon and hydrogen (hydrocarbons) and their derivatives is called
Organic Chemistry. All organic compounds contain carbon as an essential element. In short,
it is chemistry of carbon containing compounds.
Catenation
The property of forming bonds with atoms of the same element is
called catenation. It is the self-linking property of carbon.
Isomerism
Carbon compounds show phenomenon of isomerism by virtue of
which a single molecular formula may represent two or more compounds. The
compounds are said to be isomers if they have the same molecular formula
but different arrangement of atoms in their molecules or different
structural formulae.
Structural Formula
Structural formula of a compound represents the exact arrangement
of the different atoms of various elements present in a molecule of a
substance.
Condensed Formula
The formula that indicates the group of atoms joined together to
each carbon atom in a straight chain or a branched chain is called the
condensed formula.
Electronic or Dot and Cross Formula
The formula which shows the sharing of electrons between various
atoms in one molecule of the organic compound is called dot and cross formula
or electronic formula.
Homologous Series
Organic
compounds are classified into classes based on the chemical properties. Each
group or class is called homologous series which is a family or set of similar
organic compounds having a same functional group which follows a regular
structural pattern in which each successive members have a common difference of
methylene (>CH2) [or by molecular mass of 14]. Each member
of series is called a Homologue of the other”. (in Greek, homo means same and logous means ratio).
Alkyl Radicals
the radicals obtained from alkanes by
the removal of one hydrogen atom are called alkyl group or radical represented
by “R–”.
Functional Group
An atom or group of atoms or multiple
bonds whose existence in an organic compound gives distinctive qualities to
that compound is called a functional group.
Closed chain or
Cyclic compounds
These are organic compounds having a basic non-linear structure.
Closed chain or cyclic compounds are those in which the carbon atoms at the end
of the chain are not free. They are linked to form a ring. e.g. cyclobutane,
benzene, phenol etc.
Homocyclic or Carbocyclic compounds.
They have only carbon atoms in the ring. Homocyclic or carbocyclic
compounds contain rings which are made up of only carbon atoms.
Aromatic compounds/benzenoid compounds
These organic compounds contain at least one benzene ring with six carbon
atoms in their molecule. e.g. benzene and naphthalene
Alicyclic or non-benzenoid
compounds
Carbocyclic compounds which do not have benzene ring in their
molecules are called alicyclic or non-benzenoid compounds.
Heterocyclic Compounds
Cyclic compounds with a carbon ring having at least one other
electronegative atoms like O, S and N are called heterocyclic compound.
Saturated Hydrocarbons
They contain carbon-carbon single bond.
In these compounds, all the four valencies of carbon atoms are fully satisfied
through single bond
Unsaturated Hydrocarbons
They contain carbon-carbon double and
triple bonds. In these compounds, all
the four valencies of carbon atoms are fully satisfied through double and
triple bonds
Q2. What
is catenation? Give any two examples of catenation of carbon atoms.
Answer
The property of forming bonds with atoms of the same element is
called catenation. The ability of carbon atoms to join with another via
covalent bonds to create long chains or rings of carbon atoms is the primary
cause for the formation of vast number of organic compound. Straight or
branched chains are possible. e.g., butane C4H10 has two
structural formulae
Q3. Define structural
formula. Write down the structural formula, condensed formula and dot and cross
formulae of n-butane and
isobutane.
Answer
Structural formula of a compound represents the exact arrangement
of the different atoms of various elements present in a molecule of a
substance. Organic compounds may have same molecular formulae but different
structural formulae and these compounds are called isomers, e.g., butane C4H10
has two structural formulae
Q4. What
is homologous series? Name the some common homologous series with examples.
Write down the general characteristics of homologous series.
Answer
Definition of Homologous Series
Organic compounds are classified into classes based on the chemical properties. Each group or class is called homologous series which is a family or set of similar organic compounds having a same functional group which follows a regular structural pattern in which each successive members have a common difference of methylene (>CH2) [or by molecular mass of 14]. Each member of series is called a Homologue of the other”. (in Greek, homo means same and logous means ratio).
For example
Alkanes (hydrocarbon), alkenes
(hydrocarbon), alkyl halides (halogen derivative of alkanes) and alcohols are
three common homologous series having similar chemical properties showing a
common difference of methylene (–CH2–) group between their
successive members.
General characteristics
of homologous series
1.Identical structures and common difference in composition
Successive
members of the series differ by one unit of -CH2- and 14 units in
their relative molecular mass. All members of a homologous series have
identical structures.
2. General Molecular Formula
All members of
a homologous series can be expressed by a general molecular formula.
For example
general formulae of alkane, alkenes and alkynes are CnH2n+2,
CnH2n and CnH2n–2,
respectively.
3. General Method of Preparation
All members of
a homologous series can be prepared by a similar manner called general method
of preparation
4. Identical Chemical Properties
They have similar chemical properties because they contain the same
functional group.
5. Gradation in Physical Properties
There is a regular change in their physical properties; the melting
and boiling points increase gradually with the increase of molecular masses.
e.g.
m.p, b.p and
densities increase in alkane series with increase of carbon atoms.
Q5. Define
the alkyl radicals with suitable examples. How are alkyl radicals formed?
Explain different radicals of butane.
Answer
the radicals obtained from alkanes by
the removal of one hydrogen atom are called alkyl group or radical. They are generally represented by “R–”.
Alkyl radicals are derivatives of alkanes.
Butyl Radical
It is derived from butane (C4H10)
having formula C4H9–.It
may exist in 4 isomeric forms.
Butane has two isomers namely strength chain n-butane and branched
chain iso-butane. When terminal H is removed from n-butane, it is called n-butyl.
When hydrogen from central carbon is removed from n-butane, it is called sec-butyl.
When terminal H is removed from iso-butane, it is called iso-butyl. When
hydrogen from central carbon is removed from n-butane, it is called ter-butyl.
Q6. What is the difference between n-propyl and isopropyl radicals? Explain with structure.
Answer
Propyl Radical (It may exist in two isomeric forms). n-propyl
radical is formed when terminal H is removed from any one of the terminal
carbon of propane. The isopropyl radical is formed when H atom is removed from
central carbon or carbon number 2 of propane.
Q7. Differentiate
between saturated and unsaturated hydrocarbons
Answer
Difference between Saturated and Unsaturated Hydrocarbons
Q8. Identify
the functional groups in the following compounds:
Answer
(a)CH3CHO…….(Aldehydic group)
(b)CH3CH2CH2OH
…(primary alcoholic group
(c) CH3COCH3 …………(ketonic carbonyl group)
(d) CH3COOH …………(carboxylic group)
(e) CH2=CHCH3 ……. (double bond)
Q9. Name
the alkenes and alkynes having the following formula
Answer
(i) C2H4 (ethene)
(ii) C3H4 (propyne)
(iii) C2H6 (ethane)
(iv)
C6H12 (hexene or cylcohexane)
(v) C5H8 (pentyne)
(vi) C8H16 (Octene)
(vii) C7H12 (Heptane)
(viii) C6H10 (Hexyne)
Q10. Define
functional group. Write different functional groups which contain carbon,
hydrogen and oxygen.
Answer
An atom or group of atoms or multiple
bonds whose existence in an organic compound gives distinctive qualities to
that compound is called a functional group.
Functional
Groups Containing Carbon, Hydrogen and Oxygen
The organic compounds containing carbon, hydrogen and oxygen as
functional groups are alcohols, ethers, aldehydes, ketones, carboxylic acids
and esters.
Q11. What is an ester
group? Write down the formula of methyl acetate and ethyl acetate.
Answer
An ester group is the derivative of carboxylic group obtained by
replacing its H by alkyl group. Organic compounds containing the functional
group; RO>C=O or –COOR are called carboxylic acids.
Formula of Ester group ----- –COOR
Class Name --------------
Esters
Generalformula-----CnH2n+1–COOR (n=0,1,2,3,4…)
Type formula -------------- RʹCOOR
(Rʹ is H or any alkyl group; may be same or different)
Examples
Q12. What is an ether
linkage? Give its general formula. Draw the structural formulae of any two
members of this family.
Answer
The bivalent oxygen with two free valencies is called an ether
linkage denoted as – O –.
Formula of FG --------- C–O–C
or –O–
Class Name ------------ Ether
Type formula ---------- R–O–R
(R is any alkyl group, may be same or different)
General formula ----CnH2n+1–OR
(n = 1, 2, 3, 4…)
Examples
Q13.Differentiate
between aldehydic and ketonic groups? Give structural formulae of first member
of each family?
Answer
Q14. What are alkyl
halides? Give the name and formula of its functional group. Write down names,
functional group, class formula and
examples of three types of alkyl halides.
Answer
The organic compounds having functional group containing carbon,
hydrogen and halogens are called alkyl halides. Their functional group is R-X.
‘X’ may be F, CI, Br or I.
Q15. What are alcohols?
Give the name and formula of its functional group. Write down names, functional
group, class formula and
examples of three types of alcohols.
Answer
The organic compounds having hydroxyl (-OH) functional group are
called alkyl alcohols or simply alcohols. Their functional group is R-OH.
Q16. Write a detailed
note on functional groups of alkenes and alkynes.
Answer
Double Bond
Hydrocarbon consisting of double bonds between two carbon atoms in their molecules are called as alkenes, such as:
H2C = CH2 (C2H4), CH3 – CH = CH2 (C3H6)
Ethylene or Ethene Propylene or Propene
Triple Bond
Hydrocarbon consisting of triple bonds between two carbon atoms in their molecules are called as alkynes, such as:
HCºCH (C2H2) , CH3–CºCH (C3H4)
Ethyne or Acetylene Propyne
Q17. What are amines?
Explain the different types of amines giving an example of each type.
Answer
The organic compounds containing carbon, hydrogen and nitrogen as
functional group are called as amines and functional group – NH2 is
called Amino Group
Formula of FG ---------–NH2
Class Name ------------amines
Type formula ------- R–NH2
(R is any alkyl group)
General formula ----CnH2n+1–
NH2 (n = 1, 2, 3, 4)
Examples
Q18. What are
heterocyclic compounds? Give two examples.
Answer
Cyclic compounds with a carbon ring having at least one other
electronegative atoms like O, S and N are called heterocyclic compound. They
contain one or more atoms other than that of carbon atoms in their rings.
Q19. Why are benzene and
other homologous compounds of benzene called aromatic compounds?
Answer
These organic compounds contain at least one benzene ring with six
carbon atoms in their molecule. A benzene ring is made up of six carbon atoms
with three alternating double bonds. They are called aromatic because of aroma
or smell they have. For example benzene and naphthalene
Q20. How is coal formed?
What are the different types of coal? Which is the best quality of coal?
Answer
Coal was formed in nature by the
decomposition (decay) of dead plants (remnants of trees) buried under the
Earth’s crust (soil) millions of years ago. Conversion of wood into coal is
called natural carbonization. It is a very slow biochemical process taking
place in the absence of air under high pressure and high temperature over a
long period of time (about 500 millions of years). Due to different bacterial
and chemical reactions, it is first converted into a coal precursor called peat
which under high pressure and temperature gets converted into coal.
Types/Forms
Wood contains about 40% carbon, so
depending upon the extent of carbonization process, five types of coal are
found. These types differ with respect to carbon content, volatile matter and
moisture.
Q21.What is natural
gas? Give its composition. Write down the importance of natural gas?
Answer
Natural gas is a gaseous form of fossil
fuel which is a mixture of low boiling low molecular weights hydrocarbons,
methane, ethane, propane and butane. The main component about 85% is methane.
It has similar origin to coal and petroleum.
Importance of
Natural Gas (Methane)
1. It is used as a fuel for
domestic and industrial purposes.
2. It is used to prepare urea (a
fertilizer).
3. It is used as fuel in automobiles as compressed natural gas
(CNG).
4. Natural gas is also used to make carbon black. .
Q22. Encircle the
functional groups in the following compounds. Also give the names of the
functional groups?
Answer
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