Tiêu đề ORGANIC CHEMISTRY - SOME BASIC PRINCIPLES AND TECHNIQUES A-3.pdf ✅

CLASS : XIIth SUBJECT : CHEMISTRY DATE : DPP NO. : 3 1 (c) Kejldahl’s method is used for the estimation of nitrogen. The organic compound is heated with conc. H2SO4 in presence of K2SO4 (used to elevate boiling point of H2SO4) and CuSO4 (used as catalyst) to convert all the nitrogen into (NH4 )2 SO4. 2 (c) Acetone and methanol have nearly equal boiling point. thus, they are separated by fractional distillation 3 (b) Follow IUPAC rules. 4 (c) The oxygen atom in phenol has more dominating resonance effect than inductive effect. Increase in charge separation decreases the stability of a resonating structure Stability of resonating structure in decreasing order will be I > II ≡ IV > III 5 (c) The acid exist in cis and trans forms : 6 (a) Follow the mechanism of esterification. 7 (b) membered ring formed with C and N-atoms. Topic :-ORGANIC CHEMISTRY - SOME BASIC PRINCIPLES AND TECHNIQUES CH3 C C C CHCOOH H CH3 and CH3 C C CHCOOH H CH3 H Also it has asymmetric carbon atom CH3CH = HCOOH. CH3 N Pyridine is a heterocyclic compound having six SOLUTION S
8 (a) When – OH group of lactic acid is replaced by H, then chiral carbon is lost. OH H | | CH3 ―C ― COOH⟶CH3 ―C ― COOH | | H H lactic acid ∴ Its optical activity is lost. 10 (a) 2-butene exhibit rotamers. Rotamers are the isomers formed by restricted rotation. 11 (d) It contains lone pair electron on N atom. 12 (a) Ozonolysis of the compound may be given as : 13 (b) 2-aminopentane and 3-aminopentane; Position is different. 15 (c) % of H = 2 18 × weight of H2O weight of organic compound × 100 = 2 18 × 0.9 0.5 × 100 = 20% ∴ The percentage of carbon = 100 ― 20 = 80 % 16 (b) o ― and p-directing groups facilitate SE reactions whereas m-directing groups deactivate benzene ring for SE reactions. 17 (a) (+) and (-) tartaric acid does not possess any element of symmetry. 18 (b) H3C CH CH C CH CH C CH CH CH3 CH3 CH3 H H H3C CH O CH C CH CH3 H +O O+O HC C CH O H CH3 (achiral) (achiral) (achiral) Ozonolysis (O3 , Zn/H2O) + H3C CH O (achiral)
A molecule having doubly bonded carbon atoms shows geometrical isomerism only if both the doubly bonded carbon have altogether different group, i.e., baC ≡ Cab or abC = Cac or dcC = Cab. 19 (c) The chemical formula of thiourea is NH2CSNH2 so here Na2S, NaCN and NaCNS will be formed but not Na2SO4 20 (a) A white precipitate with am. AgNO3 confirms the presence of terminal alkyne.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. C C B C C A B A C A Q. 11 12 13 14 15 16 17 18 19 20 A. D A B D C B A B C A