mcqs on halogen derivatives of hydrocarbons

Test-Chemistry Halogen Derivative of HydrocarbonsQuestions: 1. A Grignard reagent is prepared by reacting magnesium with: (a) Methyl amine (b) Diethyl ether (c) Ethyl iodide (d) Ethyl alcohol 2. Reaction of chloroform with alcoholic KOH in presence of a primary aromatic amine is called: (a) Hydrolysis (b) Reduction (c) Wurtz reaction (d) Carbylamine reaction 3. Ethyl bromide reacts with lead-sodium alloy to form: (a) Tetraethyl lead (b) Tetraethyl bromide (c) Both (a) and (b) (d) None 4. The reactivity order of halide ion in alkyl halide is: (a) F > Cl > Br > I (b) Cl > F > Br > I (c) I > Br > Cl > F (d) Br > I > Cl > F 5. Non-sticking frying pans are coated with: (a) Ethylene (b) Styrene (c) Tetrafluoro ethylene (Teflon) (d) Chlorofluoro Methane 6. In the following sequence of reactions, The product (C) is: (a) Propene (b) Propyne (c) Propan-1-ol (d) Propan-2-ol 7. Chloroform on reduction with Zn and HCl(alc.) gives: (a) Formic acid (b) Chlorotone (c) Chloropicrin (d) Methylene dichloride 8. In the reaction, the product formed is: (a) 4-methyl-2-pentyne (b) Propyne (c) Propyne and propene (d) None 9. Methyl chloride on treatment with potassium cyanide followed by hydrolysis yields: (a) HCOOH (b) CH3COOH (c) CH3CN (d) CH3COOK 10. Isobutyl chloride and butyl chloride are: (a) Position isomers (b) Chain isomers (c) Functional isomers (d) Metamers 11. Carbon tetrachloride on treatment with gives: (a) Chloromethane (b) Methane (c) Chloroform (d) Methylene chloride 12. Which statement is wrong about chloroform: (a) Chloroform is used as anaesthetic (b) Chloroform has distorted shape (c) Chloroform is used as a solvent (d) chloroform has sp2-hybridised carbon atom 13. Vicinal and geminal dihalides can be distinguished by: (a) KOH(aq.) (b) KOH (alc.) (c) Zn dust (d) None 14. For the carbylamine reaction we need hot alcoholic KOH and: (a) Any amine and chloroform (b) Chloroform and silver powder (c) A primary amine and an alkyl halide (d) Any monoalkyl amine and trichloro methane 15. Victor Grignard was awarded Nobel prize for making useful compounds by joining organic compounds to: (a) Fe (b) Mg (c) Proteins (d) Na 16. Iodoform is formed when ethanol is heated with: (a) Potassium iodide and sodium hydroxide (b) Iodine and aqueous potassium hydroxide (c) Chloroform and iodine (d) Iodine and potassium iodide 17. Which does not gives iodoform reaction: (a) (b) (c) (d) 18. The reactivities of methyl chloride (A) prophyl chloride (B) and chlorobenzene (C) are in the order: (a) A > B > C (b) C > B > A (c) A > C > B (d) B > A > C 19. Iodoform test is not given by: (a) Ethanol (b) Benzophenone (c) Ethanal (d) Acetophenone 20. Iodoform gives a precipitate with heating but chloroform does not because: (a) Iodoform is ionic (b) Chloroform is covalent (c) C –I bond in iodoform is weak and C-Cl bond in chloroform is strong (d) None 21. Aryl halides are less reactive towards electrophiles than alkyl halides due to: (a) Resonance (b) Stability of carbonium ions (c) High boiling point (d) None of these 22. Which of the following does not react with benzene in presence of anhydrous : (a) (b) (c) (d) 23. The reaction is an example of: (a) Subsititution (b) Oxidation (c) Addition (d) Double decomposition 24. Methyl bromide is not used: (a) As an insecticide (b) A disinfectant (c) For dyeing clothes (d) As disinfectant for young fruit trees 25. Grignard reagent undergoes: (a) Nucleophilic substitution (b) Nucleophilic addition (c) Both (a) and (b) (d) None 26. 1,3-dibromopropane reacts with metallic zinc to form: (a) Propene (b) Cyclopopane (c) Propane (d) Hexane 27. For the reaction, the order of reactivity is: (a) HI > HCl > HBr (b) HI > HBr > HCl (c) HCl > HBr > HI (d) HBr > HI > HCl 28. Grignard reagent with hydrogen cyanide gives: (a) Aldehyde (b) Ketone (c) Both (a) and (b) (d) None 29. Which of the following do not from Grignard reagent: (a) CH3F (b) CH3Cl (c) CH3Br (d) CH3I 30. Dehydrohalogenation in haloalkanes produces: (a) A single bond (b) Direct halogenation of alkenes (c) A triple bond (d) Fragmentation 31. Preparation of alkyl halides in laboratory is least preferred by: (a) Halide exchange (b) Direct halogenation of alkanes (c) Treatment of alcohols (d) Addition of hydrogen halides to alkenes 32. The reagent used for dehalogenation of 1,2-dichloropropane is: (a) Zn dust (b) Zn – Hg (c) Na (d) Zn – Cu couple 33. The C-Mg bond in is: (a) Ionic (b) Non-polar covalent (c) Polar covalent (d) Hydrogen 34. 1,2-dibromoethane is added to prevent deposition of lead metal in: (a) Water pipes (b) Petrol engines (c) Electric heaters (d) Metal working lathe machines 35. An alkyl halide reacts with equivalent amount of NH3 to give: (a) Amide (b) Cyanide (c) Amine (d) None 36. The structural formula of the compound which yields ethylene upon reaction with zinc is: (a) (b) (c) (d) None 37. Methyl magnesium iodide on treatment with D2O furnishes a hydrocarbon alongwith Mg(OD)I. The hydrocarbon is: (a) (b) (c) (d) None 38. Correct order of reactivity for halides is: (a) Vinyl chloride > Allyl chloride > Propyl chloride (b) Propyl chloride > Vinyl chloride > Allyl chloride (c) Allyl chloride > Propyl chloride > Vinyl chloride (d) None 39. The reaction, obeys the mechanism: (a) SN1 (b) SN2 (c) SE1 (d) SE2 40. The greater the ionic character of the carbon metal bond: (a) The move reactive is the organo metallic compound (b) The less reactive is the organo metallic compound (c)Both are correct (d) None is correct 41. The molecular formula of the chlorinated acetone formed in the distillation of acetone with bleaching power is: (a) CH3COCl (b) CCl2OCl3 (c) CH2ClCOOH (d) CCl3COCH3 42. The reaction described is: (a) SE1 (b) SN2 (c) SN1 (d) SE2 Keys: 1 c 2 d 3 a 4 c 5 c 6 d 7 d 8 a 9 b 10 b 11 c 12 d 13 a 14 d 15 b 16 b 17 b 18 a 19 b 20 c 21 a 22 a 23 c 24 c 25 c 26 b 27 b 28 a 29 a 30 b 31 b 32 a 33 c 34 b 35 c 36 a 37 a 38 c 39 b 40 a 41 d 42 b Solutions: 1. 2. 3. 4. Larger is bond length, more is reactivity of halide. 5. It is a polymer and good conductor of heat. 6 7. 8. 9. -CN group hydrolyses to – COOH. 10. only chain is different. 11. 12. In , carbon is sp3- hybridized. 13. Ethanal-1-2diol Ethanal 14. Carbylamine reaction is characteristic reaction for primary amine and chloroform. 15. Grignard prepared organometallic compounds of Mg. 18. Among the primary halides reactivity order is CH3X > C2H5X > C3H7X, Also chlorobenzene is less reactive due to resonance. 20. Thus decomposition of CHI3 Occurs. 21. Aryl halides show resonance in their structure. 22. In C6H5Cl, Cl is firmly attached to C6H6 nucleus. 23. Alkenes show addition reactions. 24. It is not a colouring material. 25 26 27. HI reacts with C2H5OH even in absence of ZnX2. Larger is bond length, more is reactivity. 28 29. RMgF are unstable compounds. 30. 31. A mixture of halides is formed. 32. Zn dust removes X2 from molecule. 33. C-Mg bond is covalent but polar. 34. The lead deposited is exhausted out in from of PbBr2 35. R-X+NH3 RNH2 36. 37 38. Allyl carbonium shows resonance and thus allyl chloride is more reactive. Vinyl chloride shows resonance and thus less reactive. 39. SN2 order for reactions are 3o < 2o <1o