Tiêu đề 10. HALOALKANES AND HALOARENES.pdf ✅

BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 10. HALOALKANES AND HALOARENES #QID# 17187 (1.) In S 1N reaction on chiral centres, there is: (a.) inversion more than retention reading to partial racemization (b.) 100% retention (c.) 100% conversion (d.) 100% racemization ANSWER: a Exp: Factual #QID# 43828 (2.) 9.65 C of electric current is passed through fused anhydrous magnesium chloride. The magnesium metal thus, obtained is completely converted into a Grignard reagent. The number of moles of the Grignard reagent obtained is (a.) 5 × 10−4 (b.) 1 × 10−4 (c.) 5 × 10−5 (d.) 1 × 10−5 ANSWER: c
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 EXPLANATION: (c) MgCl2 → Mg 2+ + 2Cl − Mg 2+ + 2e − → Mg (at cathode) 2F 1 mol ∵ 2F(2 × 96500 C)deposits Mg = 1 mol ∴ 9.65 C charge will deposit Mg = 1 × 9.65 2 × 96500 = 5 × 10−5 mol RBr + Mg Dry ether → RMgBr Grignard reagent In order to prepare Grignard reagent, one mole of Mg is used per mole of reagent obtained. Thus, by 5 × 10−5 mol mg , 5 × 10−5 mole of Grignard reagent is obtained. #QID# 43805 (3.) Iodoform test is not given by (a.) HCHO (b.) CH3CHO (c.) CH3COCH3 (d.) C2H5OH ANSWER: a EXPLANATION: (a)
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 Iodoform test is given by those compounds which have – CH3CO group or on oxidation yields this group. HCHO does not give this test. #QID# 17233 (4.) Order of rate of reaction of following compound with phenyl magnesium bromide is : (a.) I > II> III (b.) II > III > I (c.) III > I > II (d.) Il > I > III ANSWER: a Exp: Factual #QID# 43782 (5.) Which of the following statements about benzyl chloride is incorrect? (a.) It is less reactive than alkyl halides (b.) It can be oxidised to benzaldehyde by boiling with copper nitrate solution (c.) It is a lachrymatory liquid and answers Beilstein’s test (d.) It gives a white precipitate with alcoholic silver nitrate
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 ANSWER: a EXPLANATION: (a) Benzyl chloride is more reactive than alkyl halides. Benzyl carbocation is stabilised by resonance hence, benzyl chloride easily gives nucleophilic substitution reaction. #QID# 17207 (6.) The S 2N reactivity order for halides is: (a.) R F R Cl R Br R I −  −  −  − (b.) R I R Br R Cl R F −  −  −  − (c.) R Br R I R Cl R F −  −  −  − (d.) R Cl R Br R F R I −  −  −  − ANSWER: b Exp: Better leaving group increases rate of S 2 N reaction. #QID# 43885 (7.) In order to convert aniline into chlorobenzene the reagent used is (a.) NaNO2/HCl, CuCl (b.) Cl2/CCl4 (c.) Cl2/AlCl3