CARBON AND ITS COMPOUNDS

1. CARBON AND ITS COMPOUNDS
(3 Mark Questions)
1. Draw the electron dot structure for the following compounds, and also find the
number of bonds in each compound
(a) Ethane (b) Propene
Answer : a) ethane C2H6----7 bonds
b) Propene C3H6----9 bonds
2. What factors makes Carbon versatile element in nature.
Answer :- 1. Carbon has the unique ability to form bonds with other atoms of
carbon, giving rise to large molecules. This property is called catenation.
2. carbon has a valency of four. ( Tetravalency ) it is capable of bonding with
four other atoms of carbon or atoms of some other mono-valent element.
3. Can form single , double, and triple bonds

2. 3. Draw the structural formula for the following (a) C6H12 (b) C6H6.
Answer :- a) C6H12
b) C6H6.
4. What is homologous series? Explain with example. Write the preceding and
following homologues for the compound C2H5OH.
Answer:- a series of compounds in which the same functional group substitutes for
hydrogen in a carbon chain is called a homologous series .
Ex: CH4 ,
C2H6
C3H8
CH3OH,C2H5OH,C3H7OH
5. What is a functional group? Identify the functional group for the following
compounds and give their IUPAC name.
(a) CH3COOH (b) C2H5OH (c) CH3COC2H5
Answer :-a) carboxylic acid, Ethanoic Acid b) alcohol , ethanol c) Ketone, butanone
6. What is meant by isomerism? Write the possible isomers for Pentane
Answer:- The property of Compounds having same molecular formula but different structural
arrangement is known as Isomerism.
Pentane C5 H12

3. 7. An esterhas a molecular formula C4H8O2 write its structural formula .what
happens when this esteris heated in the presence of NaOH solution. Give chemical
equation for the reaction and name the reaction.
Answer:- CH3COOCH2CH3
Saponification :
On treating with sodium hydroxide, which is an alkali, the ester is converted back to alcohol
and sodium salt of carboxylic acid . This reaction is called saponification because it is used in
soap making.
CH3COOC2H5 + NaOH C2H5OH + CH3COOH.
8. Give reason why saturated hydrocarbons give a clean flame while unsaturated
hydrocarbons give yellow flame.
Answer:- Saturated Hydrocarbons contains less percentage of carbon which gets completely
oxidised where as unsaturated hydrocarbons have more carbon and needs more oxygen to
completely burn
9. What is meant by hydrogenation reaction. Give its industrial application and
write the equation involved.
Answer:-Unsaturated hydrocarbons add hydrogen in the presence of catalysts
such as palladium or nickel to give saturated hydrocarbons. This reaction is commonly
used in the hydrogenation of vegetable oils using a nickel catalyst.It is industrially used to
make Vegetable ghee ( vanaspati) .

4. 10. A saturated hydrocarbon in the presence of sunlight reacts with chlorine to form
multiple compounds. Identify the type of reaction and support your answer with
suitable equations.
Answer:- Substitution reaction .
CH4 + Cl2 → CH3Cl+ HCl (in the presence of sunlight) , CH2Cl2, CHCl3, CCl4
11. Why is the conversion of ethanol to ethanoic acid an oxidation reaction? Support
your answer with chemical equation.
Answer: Alkaline potassium permanganate or acidified potassium dichromate is oxidising
alcohols to acids, that is adding oxygen to the starting material. Hence they are known as
oxidising agents, and the conversion of Ethanol to Ethanoic acid is oxidation reaction.
12. What are soaps chemically? Give reasons for formation of scum when soaps are
used with hard water. How can this problem are rectified.
Answer: The molecules of soap are sodium or potassium salts of long-chain carboxylic acids.
Formation of scum when soaps are used with hard water is caused by the reaction of soap
with calcium and magnesium salts, which cause the hardness of water. Temporary hardness of
water can be removed by boiling. In case of permanent hardness of water, water can be
softened using washing soda or an ion-exchange resin.
13. What are detergents, why they are effective in hard water. Write two
uses of detergents.
Answer: Detergents are generally ammonium or sulphonate salts of long chain carboxylic
acids. The charged ends of these compounds do not form insoluble precipitates with the
calcium and magnesium ions in hard water. Thus they remain effective in hard water.
Uses:i. Detergents are usually used to make shampoos and. ii. Products for cleaning clothes
14. Give one advantage of using soaps over detergents environmentally. Explain the
cleansing action of soap.
Answer: The main advantage of soaps over detergents is that soaps are biodegradable.
Hence,they do not cause water pollution. soaps are made from vegetable oils so are
biodegradable and hence do not pollute water as compared to detergents.
Cleansing action of soap: The ionic end of soap dissolves in water while the carbon
chain dissolves in oil. The soap molecules, thus form structures called micelles while
ionic-end faces outside. This forms emulsion in water. The soap micelle thus helps in
dissolving the dirt in water and we can wash our clothes clean.

5. 15. What is the product formed when sodium bicarbonate reacts with Ethanoic
acid. Write the equation to show the reaction.
Answer:Ethanoic acid reacts with carbonates and hydrogen carbonates to give rise to salt,
carbon dioxide and water. The salt produced is commonly called sodium acetate.
CH3COOH + NaHCO3 CH3COONa + H2O + CO2
16. A compound A on heating at 443 K in the presence of H2SO4 produces compound
B along with release of H2O. Identify A and B. write their structural formula and give
the chemical reaction for the same.
Answer:Compound A is Ethanol: C2H5OH
Compound B is Ethene: C2H4
17. An organic compound X widely used in beverages like wine and beer when
treated with sodium metal produces a compound Y along with release of a gas which
puts off a burning splinter with pop sound. Identify the compounds X and Y and also
name the gas released. Give chemical reaction.
Answer: Compound X: C2H5OH (Ethanol)
Compound Y: C2H5Ona (Sodium Ethoxide)
Gas released: Hydrogen gas.
18. How would you experimentally distinguish between an alcohol and a carboxylic
acid?
Answer: Alcohols and carboxylic acids can be distinguished by litmus test and Reaction with
sodium hydrogen carbonate
(i)Litmus test – Alcohol will have no effect on the litmus paper. Carboxylic acid acid will
change blue litmus paper into red.

6. (ii)Reaction with sodium hydrogen carbonate – Alcohol has no reaction with sodium
hydrogen carbonate (NaHCO3) but in the case of Carboxylic acid it reacts with
NaHCO3 which gives CH3COONa, CO2 and H2O. The reaction is evident as the carbon
dioxide will turn the lime water milky.
19. What is allotropy. Explain the structure of allotropes of carbon which is
responsible for properties.
Answer: Allotropy: The element carbon occurs in different forms in nature with
widely varying physical properties. Ex. Graphite and Diamond.
Structural difference between graphite and diamond: In diamond each carbon
atom is bonded to four other carbon atoms forming a rigid three dimensional
structure. In graphite, each carbon atom is bonded to three other carbon atoms
in the same plane giving hexagonal array.
20. What is covalency. Explain the properties of covalent compounds.
Answer:
Covalency: Carbon (and many other elements) share its valence electrons with other atoms of
carbon or with atoms of other elements. The type of bond thus formed is called covalent bond.
Properties of covalent compounds: i. They are poor conductors of electricity
ii. they have low melting and boiling points.
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