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: Consider the following synthesis CH3ONa + PhBr Path–II yields better yield of product than Path-I. Reason: CH3ONa is stronger base than PhONa.
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.
An incorrect statement with respect to SN1 and SN2 mechanisms for alkyl halides is (KCET 2014)
What is the name of the following reactions? NaI Dryacetone CH CH CH Br CH CH CH I -> (EAMCET 2014)
Two possible stereo-structures of CH3CHOHCOOH, which are optically active, are called (AIPMT 2015)
In an SN1 reaction on chiral centres, there is (AIPMT 2015)
The reaction of C6H5CH=CHCH3 with HBr produces (AIPMT 2015)
Consider the reaction, CH CH CH Br NaCN CH CH CH CN NaBr -> This reaction will be the fastest in (NEET 2016)
For the following reactions, (i) CH CH CH Br KOH CH CH CH KBr H O -> (ii) (iii) Which of the following statements is correct? (NEET 2016)
Identify A and predict the type of reaction. (NEET 2017) (a) and elimination addition reaction (b) and cine substitution reaction. (c) and cine substitution. (d) and substitution reaction.
Neopentyl chloride reacts with benzene in presence of a Lewis acid (AlCl3) to form (JIPMER 2018) (a) (b) (c) (d)
Identify the major product that is obtained on treatment of CH CH CH F CH with CH O / CH OH is (JIPMER 2018) (a) CH CH CH OCH CH (b) CH CH CHCH (c) CH CH CH CH (d) CH CH CH CH OCH SOLID STATE
CH OH/H (i) CO Mg/ether (ii)H O CH Br P ->->-> Which is the product ‘P’ in the above reaction? (JIPMER 2018)
Among the following, the suitable reagent for Wurtz reaction is (JIPMER 2018)