Explain the following :
(a) The dipole moment of chlorobenzone is lower than that of cyclohexyl chloride.
(b) Alkyl halides, though polar, are immiscible with water.
(c) Grignard reagents should be prepared under anhydrous condition.

Explain why (i) the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride? (ii) alkyl halides, though polar, are immiscible with water? (iii) Grignard reagents should be prepared under anhydrous conditions?

Give reasons: (i). C-Cl bond length in chlorobenzene is shorter than C-Cl bond length in CH_(3)-Cl (ii). The dipole moment of chlorobenzene is less than of cyclohexyl chloride. (c). S_(N^(1)) reactions are accompanied by racemisation is optically active alkyl halides.

(a) Explain why cleavage of phenyl ethers with HBr always produces phenol and alkyl bromides and not bromobenzene and alkanols. (b) Give reasons for the following: (i) The dipole moment of diethyl ether (1.18D) is lower than that of water (1.84D). (ii) The C-O-C bond angle in ethers is higher than H-O-H angle in water though oxygen is sp3 hybridized in both the cases. (iii) Dimethyl ether is completely miscible with water but diethyl ether is soluble in water to a small extent.

Give reasons for the following (a) No visible reaction occurs when aluminium is left in contact with conc HNO_(3) . (b) The hydroxides of Al and Fe are insoluble in water. However, NaOH is used to distinguish one from another. ( c) Anhydrous AlCl_(3) cannot prepared by heating hydrated aluminium chloride. (d) Aluminium vessels should not be cleaned with cleansing agent containing washing soda. ( e) Duralumin is used in aircraft industry.

Explain the following observations: (a) Azide ion (N_(3)) react with 2- bromopentane thousand times faster than with neopentyl bromide in a S_(N)2 reaction through former is a secondary halide while latter is primary. (b) What will happen to the stereochemistry of product of the following reaction: (c) What will happens to the rate if the concentration of alkyl bromide in (b) is doubled? (d) Wha will happen to the rate if the concentration of azide ion in (b) is doubled? (e) How the sign of optical rotation of reactant and product are related in (b) (f) When allowed to stand in dilute H_(2)SO_(4) laevo-rotatory 2-butanol slowly loss optical activity.

How many statements are true for the following pair of compounds ? Cis Trans (i) The dipole moment of trans isomer is zero (ii) The boiling point of cis isomer is more than trans isomer (iii) Cis isomer is more stable than the trans isomer (iv) These are also called configurational diastereomers (v) These are readily interconvertible under normal conditions (vi) The melting point of trans isomer is more than the cis isomer (vii) Trans isomer is more soluble than cis isomer in polar solvents

Explain the following: (a) In the preparation of HI from KI , phosphoric acid is preferred to sulphuric acid. (b) Boiling point of HCl is lower than HF . (c ) Bleaching powder loses its bleaching property when kept in an open bottle for a long time.

Of the following statements , which are true for S_(N)2 reaction. (a) Tertiar alkyl halides reacts faster than secondary. (b) The absolute configuration of product is opposite to that of the reactant when an optically active substrate is used. (c) The used shows first order kinetics. (d) The rate of the reaction depends markedly on the nucleophilicity of the attacking reagent. (e) The mechanism is one step. (f) Carbocations are intermediate. (g) Rate prop [Alkyl][halides] (h) The rate of the reaction depends on the nature of the leaving group.

Explain the following observation : a. When pent -1 en -4- yneistrested with HBr in molar proportion, the addition takes place on the double bond and not on the triple bond, thereby, yielding the porduct , b. The (C=-C) bond length in propene is shorter than expected. c. Whey benzyl carbocation is more stable than ethyl carbocation ? d. Why does but -2- ene exhibit cis - trans isomerism but but -2- yne does not ? e. CI_(2)C=C C I_(2) does not add CI_(2) under usual conditions but adds in the presence of AICI_(3) .

Give reasons for the following (a) The presence of -NO_2 group at ortho or para position increases the reactivity of haloarenes towards nucleophilic substitution reactions . (b) p-dichlorobenzene has higher melting point than of ortho or meta isomer . ( c) Thionyl chloride method is preferred for preparing alkyl chloride from alcohols.