Saturday, October 1, 2011

10th Solved Extra Score Paper(Carbon and its Compounds)

Q.1 Why is carbon tetravalent ?

Answer:  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. 

Carbon+and+its+compound.png (320×197)Answer:  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 ? 

Answer: 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? 

Answer:  Groundnut oil is unsaturated in nature . 

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

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

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

Answer:  Benzene 

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

Answer:  14 mass units. 

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

Answer:  C3H4 has triple bond in the formula .

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

Answer:  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 ? 

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

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

Answer :  Nickel. 

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

Answer:  C4H9OH Butanol 

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

Answer:  CO2 (carbon dioxide). 

Q.14 What is SCUM ?

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

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

Answer: 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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