19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Assertion: Activity of an enzyme is pH-dependent. Reason: Change in pH affects the solubility of the enzyme in water.
Assertion: Chloral reacts with phenyl chloride to form DDT. Reason: It is an electrophilic substitution reaction
Assertion: A dichlorobenzene is slightly more reactive than chlorobenzene towards an aromatic nucleophilic substitution reaction. Reason: Chlorine has electron withdrawing effect on aromatic ring.
Assertion: p-nitrochlorobenzene is more reactive than m-nitrochlorobenzene towards aromatic nucleophilic substitution reaction. Reason: Nitro group from para and meta positions has opposite effect in aromatic nucleoph…
Assertion: The reaction of bulky base such as potassium tertiary butoxide [(CH3)3CO–K+] with secondary alkyl halides gives predominantly E2 elimination product rather than SN2 substitution product. Reason: The transit…
Assertion: Ph–CO–CH2CH2OCH3 has greater reactivity for E1CB than for E2 reaction. Reason: A poor leaving group and acidic —H favour E1CB mechanism.
Assertion: Treatment of either enantiomer of 2-chlorobutane with ethanolic KOH results in trans-2- butene as major elimination product. Reason: Elimination with ethanolic KOH is a bimolecular reaction.
Assertion: Chlorination of allylic hydrogen is difficult than vinylic hydrogen. Reason: Allyl radical is stabilised by resonance.
Assertion: SN2 reaction of CH3––Br is faster in Cl CH S – SCH3 Cl (CH ) CHS 3 2 – SCH(CH ) 3 2 DMSO than in H2O. Reason: DMSO has greater capability to solvate nucleophile.
Assertion: Allyl halide (CH2=CH–CH2X) is more reactive than CH3CH2CH2X in a SN2 reaction. Reason: Allyl halide forms a resonance stabilized carbocation
Assertion: Consider the following SN2 reactions. (I) and (II) Reaction (II) occurs at a faster rate than (I) Reason: Anion of reaction (II) is a stronger base than the anion of reaction (I).
Assertion: Rate of reaction is dependent only on the concentration of nucleophile in SN1 reactions. Reason: Polar solvent favors SN1 reaction.
Assertion: Heavy metal ions Ag + or Pb 2+ decrease SN1 reactivity. Reason : They aid ionisation of RX.
Assertion: In SN1 mechanism, the product with inversion of configuration is obtained in a higher amount compared to the product with the retention of configuration. Reason: Front side attack of nucleophile is hindered…
Assertion: Benzyl bromide when kept in acetone – water, produces benzyl alcohol. Reason: The reaction follows SN2 mechanism.
Assertion: Consider the following synthesis CH3ONa + PhBr Path–II yields better yield of product than Path-I. Reason: CH3ONa is stronger base than PhONa.
Which of the following bases would give the best yield for the substitution product when reacted with 2-chloropropane?
Which of the following is the best synthesis of compound shown? (a) (b) (c) (d)
CH CH CH CH Br DMF CH CH O -> This reaction would follow which of the following pathway predominantly?
1-hexene is formed when methoxide reacts with
Debromination of meso dibromobutane will give the product as:
Find the major product of the following reaction: (a) (b) (c) (d)
CH CD CH CHCD3 CH CD C CHCD CD CD CH CHCH3 CH CD CHCH2CD3 SOLID STATE The major product obtained when this substrate is subjected to E1 reaction will be (a) (b) (c)
An SN2 reaction at an asymmetric carbon of a compound always gives
The organic chloro compound, which shows complete stereochemical inversion during an SN2reaction is