JEE Chemistry - MCQ Practice Questions

Both Tollens and Fehling reagents give positive test with aldehydes (silver mirror and red precipitate respectively) but not with ketones.

Chromic acid oxidizes primary alcohols to carboxylic acids. The aldehyde is an intermediate which is further oxidized.

Addition to alkenes follows electrophilic addition mechanism with carbocation formation, leading to Markovnikov's product.

Acetone (CH3-CO-CH3) has α-hydrogen atoms and can exist in equilibrium between keto and enol forms.

NO2+ (nitronium ion) is an electrophile with positive charge, not a nucleophile. All others have lone pairs or negative charge.

Williamson ether synthesis uses SN2 reaction between alkoxide (R-O-) and alkyl halide (R'-X) to form R-O-R'.

Tertiary carbocation (CH3)3C+ is most stable due to maximum hyperconjugation and inductive stabilization from three alkyl groups.

But-2-ene (CH₃-CH=CH-CH₃) on ozonolysis gives two identical fragments, each being acetaldehyde (CH₃CHO). The double bond cleaves symmetrically.

tert-Butyl bromide is a tertiary alkyl halide. Tertiary substrates preferentially undergo SN1 mechanism due to stable tertiary carbocation formation. SN2 is hindered by steric effects.

Tollens test is positive for aldehydes. Propanal (CH₃CH₂CHO) is an aldehyde and gets oxidized to carboxylic acid, reducing Ag⁺ to Ag (silver mirror). Acetone is a ketone, ether and alcohol do not give positive test.

The parent chain is butane (4 carbons). Numbering from the end nearest to substituent gives Br at position 2. IUPAC name is 2-bromobutane. Option D is a common name.