SHORT QUESTIONS

1. What are hydrocarbons ?
   
   ANS : The compounds containing atoms of carbon and hydrogen only are called hydrocarbons.
   


2. What is a functional group ?
   
   ANS : An atom or a group of atoms which is responsible for chemical reactions of organic compounds is called a functional group. OR An atom or a group of atoms present in a compound which is responsible for the chemical properties of that compound is called a functional group.
   


3. Organic compounds containing same functional group show similar chemical properties. True or false ?
   
   ANS : This is a true statement.
   


4. Ethane reacts more rapidly than ethyne. True or false ?
   
   ANS : This is a false statement.
   


5. What is the general formula of alcohols ?
   
   ANS : The general formula of alcohols is C_nH_{2n + 1}OH or R-OH where R represents the alkyl group (C_nH_{2n + 1}) and n=1,2,3,...
   


6. Write the formula of ethanoic acid.
   
   ANS : The formula of ethanoic acid is CH₃COOH.
   


7. Mention first four alkanes.
   
   ANS : Methane, ethane, propane and butane are first four alkanes.
   


8. Mention first four alcohols.
   
   ANS : Methanol, ethanol, propanol and butanol are first four alcohols.
   


9. By which two methods can ethyl alcohol (ethanol) be prepared ?
   
   ANS : Ethyl alcohol can be prepared by (i) Fermentation of carbohydrates (ii) Hydration.
   


10. Which enzyme converts milk into curd ?
    
    ANS : Lactase converts milk into curd.
    


11. What does lactase do during the conversion of milk into curd ?
    
    ANS : Lactase converts lactose into lactic acid.
    


12. What is fermentation ?
    
    ANS : Fermentation is a slow process of breaking down of carbon compounds in the presence of enzymes amd in the absence of oxygen.
    


13. Write the reaction of hydration of ethene.
    
    ANS :
    
    
    


14. What is the boiling point of pure ethanol ?
    
    ANS : The boiling point of pure ethanol is 78°C.
    


15. Write the equation for the combustion of ethanol.
    
    ANS :
    
    
    


16. Write the formula of sodium ethoxide.
    
    ANS : The formula of sodium ethoxide is CH₃CH₂ONa.
    


17. What is obtained when ethanol reacts with sodium metal ?
    
    ANS : When ethanol reacts with sodium metal; sodium ethoxide and hydrogen are obtained.
    


18. What is the formula of ethanal ?
    
    ANS : The formula of ethanal is CH₃CHO.
    


19. What is the formula of ethylethanoate (ethyl acetate) ?
    
    ANS : The formula of ethylethanoate is CH₃COOCH₂CH₃.
    


20. What is esterification ?
    
    ANS : The process in which an alcohol reacts with an organic acid to form an ester in presence of a small amount of conc. sulphuric acid is called Esterification.
    


21. What is 'rectified spirit' ?
    
    ANS : Ethyl alcohol containing 5% water is called 'rectified spirit'.
    


22. What is 'Denatured' ethyl alcohol ?
    
    ANS : 'Denatured' ethyl alcohol is the ethyl alcohol to which poisonous methanol or CuSO₄ has been added to prevent people from consuming it.
    


23. Write symbolically the functional group 'carbonyl'.
    
    ANS : The functional group carbonyl is >C=O.
    


24. Write the formula of formaldehyde (methanal).
    
    ANS : The formula of formaldehyde is
    
    
    


25. Write the formula of acetone.
    
    ANS : The formula of acetone (propanone) is
    
    
    


26. Write the common as well as IUPAC name of the compound whose formula is HCHO.
    
    ANS : The common name of HCHO is formaldehyde and its IUPAC name is methanal.
    


27. Write the common names of first four aldehyde compounds.
    
    ANS : The common names of first four aldehyde compounds are : formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde.
    


28. Write the chemical formula of butanal.
    
    ANS : The chemical formula of butanal is CH₃CH₂CH₂CHO.
    


29. Which catalyst is used to prepare formaldehyde from methanol ?
    
    ANS : Silver oxide, Ag₂O is used as catalyst to prepare formaldehyde from methanal
    


30. Write the chemical equation of oxidation of methanol to methanal.
    
    ANS :
    
    
    


31. What does oxidation of methanal yield ?
    
    ANS : The oxidation of methanal yields methanoic acid.
    


32. Mention the oxidising agents used for the oxidation of methanal.
    
    ANS : Tollen's reagent, potassium permanganate solution, solution of potassium dichromate, etc rae used as oxidising agents for the oxidation of methanal.
    [The Gujarati version of text book (GSEB) mentions two names : Ammoniacal silver nitrate (Tollen's reagent) and Fehling's reagent].
    


33. Write the chemical formula of methanal cyanohydrin.
    
    ANS : The formula of methanal cyanohydrin is
    
    
    


34. What is formalin ?
    
    ANS : Formalin is 40% aqueous solution of formaldehyde.
    


35. Name the process by which acetone (propanone) is prepared.
    
    ANS : Acetone is prepared by Fischer-Tropsch process.
    


36. Which catalyst is used in Fischer-Tropsch process to prepare acetone ?
    
    ANS : Cobalt oxide (CoO) is used as catalyst in Fischer-Tropsch process to prepare acetone.
    


37. What is the formula of iso-propyl alcohol (2-propanol) ?
    
    ANS : The formula of iso-propyl alcohol is
    
    
    


38. What is the formula of acetone cyanohydrin ?
    
    ANS : The formula of acetone cyanohydrin is
    
    
    


39. Write the general formula of carboxylic acid (organic acids).
    
    ANS : The general formula of carboxylic acids is
    C_nH_{2n + 1}COOH [n=0,1,2,3,...].
    


40. What is the common name of methanoic acid ?
    
    ANS : The common name of methanoic acid is formic acid.
    


41. Which bacteria convert ethanol into acetic acid ?
    
    ANS : Acetobactor convert ethanol into acetic acid.
    


42. Which catalyst is used in the preparation of acetic acid from methanol.
    
    ANS : I₂-Rh (Iodine-rhodium) is used as a catalyst in the preparation of acetic acid from methanol.
    


43. Acetic acid is immiscible with water. True or false ?
    
    ANS : This is a false statement.
    


44. Write the equation showing reaction between acetic acid and sodium metal.
    
    ANS :
    
    
    


45. What is neutralisation reaction ?
    
    ANS : A neutralisation reaction is the one in which an acid reacts with a base to form a salt and water.
    


46. Give the example of the neutralisation reaction of acetic acid.
    
    ANS :
    
    

    CH₃COOH + NaOH → CH₃COONa + H₂O

    .
    


47. What is sodalime ?
    
    ANS : Sodalime is a mixture of NaOH and CaO in the ratio of 3:1 (NaOH + CaO).
    


48. What is produced when acetic acid reacts with sodalime ?
    
    ANS : Methane and carbon dioxide are produced when acetic acid reacts with sodalime.
    


49. What is decarboxylation reaction ?
    
    ANS : The removal of carbon dioxide (-COO part) from the carboxyl group of an organic acid is called decarboxylation reaction.
    


50. What is vinegar ?
    
    ANS : Vinegar is 4 to 6 % aqueous solution of acetic acid.
    


51. What do we mean by man-made materials ?
    
    ANS : New substances prepared from the natural raw materials are called man-made materials.
    


52. What are polymers ?
    
    ANS : Polymers are long-chain compounds with many smaller units called monomers.
    


53. Mention some synthetic fibres.
    
    ANS : Rayon, nylon, polyester, etc. are synthetic fibres.
    


54. Give some examples of plastics.
    
    ANS : Polythene, polyvinylchloride (PVC), TEFLON, Bakelite, melamine, etc. are examples of plastics.
    


55. Mention types of plastics.
    
    ANS : The types of plastics are : (i)thermoplastic
    (ii)thermosetting plastics.
    


56. What is a thermoplastic ?
    
    ANS : Plastics which become soft on heating and regain original state (solid) on cooling are called thermoplastics.
    


57. Give examples of thermoplastic.
    
    ANS : Polythene, PVC, polystyrene, etc. are examples of thermoplastic.
    


58. What is a thermosetting plastic ?
    
    ANS : Polymers which do not soften on heating at high temperature are called thermosetting plastics.
    


59. Give examples of thermosetting plastics.
    
    ANS : Bakelite and melamine are examples of thermosetting plastics.
    


60. How rae polymers classified ?
    
    ANS : Polymers are classified on the basis of the reaction of their formation into 'Addition polymer' and 'Condensation polymer'.
    


61. What is the chemical name of TEFLON ?
    
    ANS : The chemical name of TEFLON is Polytetrafluoroethene.
    


62. What is an addition polymer ?
    
    ANS : Addition polymers are formed by addition of one or more than one (same or different) unsaturated monomer having double or triple bond.
    


63. Mention monomers of natural rubber and artificial rubber.
    
    ANS : Isoprene is the monomer of natural rubber and chloroprene is the monomer of artificial rubber.
    


64. Write the formula of isoprene.
    
    ANS : The formula of isoprene is
    
    
    


65. Write the formula of butadiene.
    
    ANS : The formula of butadiene is CH₂=CH-CH=CH₂.
    


66. What is used as an alternative to rubber ?
    
    ANS : Polybutadiene is used as an alternative to rubber.
    


67. What is the formula of chloroprene ?
    
    ANS : The formula of chloroprene is
    
    
    


68. Give examples of addition polymers.
    
    ANS : Polythene, PVC, rubber, polybutadiene, etc. are examples of addition polymers.
    


69. From what is natural rubber obtained ?
    
    ANS : Natural rubber is obtained from the latex of rubber trees.
    


70. What are the defects of natural rubber ?
    
    ANS : Natural rubber has low elasticity and low strength (it is less tough).
    


71. Between which temperature range is the elasticity of natural rubber maintained ?
    
    ANS : The elasticity of natural rubber is maintained between 10°C to 60°C.
    


72. What is the effect of temperature on natural rubber ?
    
    ANS : Natural rubber becomes brittle below 10°C and soft above 60°C.
    


73. What is vulcanisation of rubber ?
    
    ANS : Vulcanisation of rubber is the process in which rubber is mixed with sulphur powder and heated upto 100 - 140°C.
    


74. Why is rubber vulcanised ?
    
    ANS : Rubber is vulcanised to improve its properties of elasticity and hardness.
    


75. What is a condensation polymer ?
    
    ANS : A polymer formed by the condensation of two or more than two monomers with the elimination of a simple molecule like water or ammonia, is called condensation polymer.
    


76. Give examples of condensation polymer.
    
    ANS : Polyester and polyamides are examples of condensation polymer.
    


77. Which types of compounds react to form polyester ?
    
    ANS : A compound containing two carboxylic acid groups and another compound containing two hydroxyl groups react to form polyester.
    


78. Which types of compounds react to form polyamides ?
    
    ANS : A compound containing two carboxylic acid groups and another compound containing two amino groups react to form polyamides.
    


79. Nylon is an addition polymer. True or false ?
    
    ANS : This is a false statement.
    


80. Nylon is a polyamide. True or false ?
    
    ANS : This is a true statement.
    


81. What is soap ?
    
    ANS : Soap is a sodium or potassium salt of higher fatty acids like stearic acid or palmitic acid.
    


82. What is saponification ?
    
    ANS : saponification is a process of making soap by reaction between a vegetable oil and sodium hydroxide.
    


83. What are detergents chemically ?
    
    ANS : Chemically detergents are sodium salts of sulphonates.
    


84. Mention the functional groups of soap and detergent.
    
    ANS : The functional group of a soap is -COONa and that of a detergent is -SO₃Na.
    


85. Which are two parts of a soap or detergent ?
    
    ANS : A long chain of hydrocarbon which is nonpolar and water-repelling and -COONa (in soap) or -SO₃Na (in detergent) which is polar and has affinity for water are the two parts of a soap or detergent.
    


86. Which functional group is present in the following compounds ? (i)CH₃CH₂CH₂OH (ii) CH₃COCH₃ (iii) CH₃CHO (iv) CH₃CH₂COOH (v) CH₃CH₂CH=CH₂.
    
    ANS : (i) Alcohol (ii) ketone (iii) aldehyde (iv) carboxylic acid (v) hydrogen.
    


87. Which gas is produced during the process of fermentation ?
    
    ANS : Carbon dioxide gas is produced during the process of fermentation.
    


88. Which compound is obtained during the hydration of ethene ?
    
    ANS : Ethyl alcohol is obtained during the hydration of ethene.
    


89. Write the names of products of oxidation reaction of ethanol in presence of KMnO₄ and chromium oxide.
    
    ANS : The product obtained by oxidation of ethanol in presence of KMnO₄ is ethanoic acid whereas in presence of chromium oxide we get ethanal.
    


90. Write the equation of the reaction of reduction of methanal.
    
    ANS :
    
    
    


91. What is obtained as by-product during preparation of soap ?
    
    ANS : Glycerol is obtained as by-product during preparation of soap.
    


92. How can you convert propanone to ethanoic acid ?
    
    ANS : Propanone can be converted to ethanoic acid by its oxidation using alkaline potassium permanganate.