Organic Chemistry Class 9 Extra Questions and Answers Kerala Syllabus Chemistry Chapter 8

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Kerala Syllabus Std 9 Chemistry Chapter 8 Organic Chemistry Extra Questions and Answers

Question 1.
Write the condensed formula of the following organic compounds

Answer:
a) CH₃-CH₂-CH₃
b) CH₂=CH₂
c) CH₂=CH-CH₃
d) CH≡CH

Question 2.
Find out the missing compounds in the given homologous series. To which category do these compounds belong and write the general formula of each series.
(i) C₂H₂, C₃H₄, ………, C₅H₈,…..
(ii) ………., C₂H₆, C₃H₈, ……….., C₅H₁₂
(iii) C₃H₆, C₄H₈, ……….., ………….., C₇H₁₄
Answer:
(i) C₂H₂, C₃H₄, C₄H₆, C₅H₈, C₆H₁₀ – Alkynes – C_nH_2n+2

(ii) CH₄, C₂H₆, C₃H₈, C₄H₁₀, C₅H₁₂ – Alkanes – C_nH_2n+2

(iii) C₃H₆, C₄H₈, C₅H₁₀, C₆H₁₂, C₇H₁₄ – Alkenes – C_nH_2n

Question 3.
Write the molecular formula of the given hydrocarbons

Answer:
a) C₅H₈
b) C₄H₁₀
c) C₃H₆
d) C₂H₄

Question 4.
Draw the structures and write the condensed formula of the given hydrocarbons.
a) Propene
c) Ethene
b) Propyne
d) Ethyne
Answer:

Question 5.
Match the following

A	B	C
Alkane	CnH2n	Butane
Alkene	CnH2n-2	Ethyne
Alkyne	CnH2n+2	Propene

Answer:

A	B	C
Alkane	CnH2n+2	Butane
Alkene	CnH2n	Propene
Alkyne	CnH2n-2	Ethyne

Question 6.
C₄H₁₀ and C₅H₁₂ are homologues. What conclusions can be drawn from this statement?
Answer:

• They can be represented using a general formula.
• There is a difference in the -CH₂– group between them.
• Shows similarity in chemical properties.
• Regular gradation in physical properties.

Question 7.
Which among the given hydrocarbons does not belong to the same homologous series?
C₂H₆, C₃H₈, C₄H₈, C₅H₁₂
Answer:
C₄H₈

Question 8.
The first member of the alkyne family is _____________
(CH, C₂H₂, C₃H₄, C₄H₆)
Answer:
C₂H₂

Question 9.
Draw the structure of an alkane, alkene and alkyne containing 5 carbon atoms.
Answer:

Question 10.
Write the IUPAC name of the following compounds.
a) CH₃-CH₂-CH₂-CH₃
b) CH₂=CH-CH₃
c) CH₃-CH₃
d) CH≡CH
Answer:
a) Butane
b) Propene
c) Ethane
d) Ethyne

Question 11.
Write the IUPAC names,

Answer:
a) Propene
b) Propyne

Question 12.
Analyse the two compounds given

a) To which category do these compounds belong?
b) Write the name and molecular formula of A and B.
Answer:
a) A – Alicyclic; B – Aromatic
b) A – C₆H₁₂ – Cyclohexane
B – C₆H₆ – Benzene

Question 13.
Hints about a hydrocarbon is given
• Three carbon atoms in the main chain
• A double bond is present between two carbon atoms
a) Draw the structure of the hydrocarbon.
b) Write the IUPAC name.
c) Write the condensed formula.
d) Write the molecular formula
e) Write the name and draw the structure of the cyclic compound having the same molecular formula.
Answer:

Question 14.
Hints about a hydrocarbon is given
• Four carbon atoms are there in the main chain
• A double bond is present between two carbon atoms
a) Write the structural formula of the open-chain hydrocarbon in two ways.
b) Write the condensed formula of both the structures.
c) Write the molecular formula and IUPAC name.
d) Draw the structure of a cyclic compound having the same molecular formula. Ans:
Answer:

Question 15.
From the given compounds, which one is aromatic?
a) Butane
b) Cyclopropane
c) Ethane
d) Benzene
Answer:
d) Benzene

Question 16.
IUPAC name of CH₃—CH=CH₂ is ______________
a) Propane
b) Propene
c) Propyne
d) Cyclopropane
Answer:
b) Propene

Question 17.
The structure of a hydrocarbon is given below

a) Which type of covalent bond is present in this compound?
b) What are hydrocarbons?
c) Draw the structure of a ring hydrocarbon having three carbon atoms.
d) The ability of the atoms of an element to combine among themselves is called _________ .
Answer:
a) Single bond
b) Compounds containing only carbon and hydrogen
c)
d) Catenation

Question 18.
Analyse the given structure

a) How many carbon atoms are there in the main chain of the compound.
b) Write the IUPAC name of this compound.
Answer:
a) 5 carbon atoms
b) 3- Methylpentane

Question 19.
The molecular formula of two hydrocarbons is given
a) C₄H₈
b) C₃H₈
Write the structural formula, condensed formula and IUPAC name of them.
Answer:

Question 20.
Draw the structures of benzene(C₆H₆) and cyclohexane(C₆H₁₂).
Answer:

Question 21.
Match the following

A	B	C
Coal	Greenhouse effect	Butane
LPG	Carbonisation	Methane
Global warming	Domestic fuels	Anthracite

Answer:

A	B	C
Coal	Carbonisation	Anthracite
LPG	Domestic fuels	Butane
Global warming	Greenhouse effect	Methane

Question 22.
Name the most abundant fossil fuel.
Answer:
Coal.

Question 23.
Name the method used for separating components from petroleum.
Answer:
Fractional distillation.

Question 24.
Name the process by which coal formation takes place.
Answer:
Carbonisation.

Question 25.
Write the different forms of coal.
Answer:
Anthracite, Bituminous coal, Lignite, and Peat.

Question 26.
Name some of the major fossil fuels.
Answer:
Coal, Petroleum end natural gas.

Question 27.
Compare LPG, LNG and CNG.
Answer:

LPG	LNG	CNG
Liquified Petroleum Gas.	Liquified Natural Gas is manufactured by liquifying gas under very high pressure.	Compressed Natural Gas.
Domestic fuel.	Ecofriendly fuel: Emits less carbon than other fuels.	Used as pollution-free vehicle fuel.
The main component is butane.	The main component is methane gas.	The main component is methane gas.

Question 28.
Explain about the greenhouse effect and global warming.
Answer:
Greenhouse gases (carbon dioxide, methane, nitrous oxide) present in the atmosphere trap a part of the infrared radiation that is reflected and radiated from the earth. As a result, the temperature of the earth increases, and this is called the greenhouse effect.

The phenomenon of an increase in the average temperature of the earth and the atmosphere is called global warming.

Question 29.
a) Write the consequences of global warming in nature,
b) Write two measures to prevent global warming.
Answer:
a) Consequences of global warming are

• Melting of ice glaciers results in flooding.
• Results in drastic climatic changes.
• Affects agriculture.

b) Measures to prevent global warming are

• Reduce the use of fossil fuels.
• Promote afforestation.
• Reduce deforestation.