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CBSE Notes 2011-2012

Chemistry x CARBON AND ITS COMPOUNDS short type important questions

Q.1 Why is carbon tetravalent ?

Ans 1:Carbon atom has 4 electrons in the outermost shell.It needs 4 more electrons to complete its octet. Therefore , carbon is tetravalent .

Q.2 The formula of a hydrocarbon is Cn H2n. Name the family to which it belongs and also predict its nature.

Ans 2: The hydrocarbon belongs to alkenes It is unsaturated in nature .

Q.3 What is the valency of carbon in CH3-CH3, CH2=CH2 and HC=CH ?

Ans 3: The valency of carbon in all its compounds whether saturated or unsaturated is 4.

Q.4 Out of butter and ground nut oil , which is unsaturated in Nature?

Ans 4: Groundnut oil is unsaturated in nature .

Q.5 Why is high temperature not favourable for alcoholic fermentation?

Ans 5: The high temperature destroys the enzymes which are needed to carry fermentation .

Q.6 Name a cyclic unsaturated hydrocarbon, containing three double bonds?

Ans 6: Benzene

Q.7 What is the difference in the molecular mass of any two adjacent homologues?

Ans 7 : 14 mass units.

Q.8 Which has triple bond ; C2H4 ,C3H6 and C3H4 ?

Ans 8:C3H4 has triple bond in the formula .

Q.9 Which substance is added to denature ethyl alcohol?

Ans 9: A small amount of methyl alcohol , pyridine or copper sulphate is added to denature ethyl alcohol .

Q.10 Which ions are responsible for making water hard ?

Ans 10: Ca2+ and Mg2+ ions are responsible for making water hard.

Q.11 Name the catalyst commonly used in hydrogenation of oil to form fats?

Ans 11:Nickel.

Q.12 Write the name and molecular formula of alcohol derived from butane ?

Ans 12: C4H9OH Butanol

Q.13 Which gas is evolved when sodium carbonate or bicarbonate is added to ethanoic acid ?

Ans 13 : CO2 (carbon dioxide).

Q.14 What is SCUM ?

Ans 14: Scum is precipitate of Calcium and Magnesium salt of organic fatty acids.

Q.15 What are hydrophobic and hydrophilic parts in soaps?

Ans 15: The alkyl group(R) consisting of long chain of carbon atom is hydrophobic part while COONa group is hydrophilic in nature
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