Tiêu đề HYDROCARBONS A-8.pdf ✅

CLASS : XIIth SUBJECT : CHEMISTRY DATE : DPP NO. : 8 1 (a) Aromatic compounds have delocalised π-electrons. Out of given choices cyclohexane, CH4, C2H6 and benzene, only benzene is aromatic compound. Benzene has six delocalised π-electrons. 2 (c) Trivial name is allyl. 3 (d) These are all facts. 4 (a) The reactivity order for sulphonation of H-atom in alkane : 3>2>1. 5 (a) As the –CH3 group increases boiling point decrease 7 (b) Alcoholic KOH is a dehydrohalogenating reagent, so when n-propyl bromide is treated with alcoholic KOH, propene is obtained. CH3CH2CH2Br + alc KOH n-propyl bromide →CH3CH = CH2 +HBr propene 8 (b) Knowing the number and arrangement of carbon atoms in aldehydes and ketones the structure of the original alkene can be worked out. 9 (a) A method used during II world war. 10 (d) Ozonolysis of these two produces different products. 12 (c) For simplest alkyne n=2; thus, alkyne is CnH2n―2 or C2H2. CH2 CH C CH CH3 CH3 O3 Zn/CH3COOH CH3 C H O O C H + H + CH3COCHO Topic :-HYDROCARBONS SOLUTION S
14 (d) Alkene is CH3CH = CHCH3, a symmetrical alkene and therefore alcohol is, 15 (b) Cyclodecapentaene and Cyclooctatetraene both are nonaromatic. Cyclobutadiene is antiaromatic while benzene having 6π-electrons is aromatic 16 (d) CH3CH2CH2CH2CH2CH3; (CH3 )2CHCH2CH2CH3; CH3CH2CH(CH3 )CH2CH3; (CH3 )3CCH2CH3;(CH3 )2CHCH(CH3 )2 17 (f) These are facts about alkanes. 18 (c) Due to resonance, benzene is quite stable and inspite of three double bonds does not decolourise B r2 water. 19 (c) Follow peroxide effect. 20 (d) The reaction is Wurtz’s type reaction. Cl Br + 2 Na Ether + NaCl + NaBr CH3CH2CHCH3 OH which will give alkene-2 as major product.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. A C D A A C B B A D Q. 11 12 13 14 15 16 17 18 19 20 A. B C C D B D D C C D