cbse chemistry class 10 Carbon and its Compounds
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?
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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