Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

93901.

(+)-2-iodobutane loses its optical activity when Nal is added to its acetone solution. Explain.

Answer»

Solution :(+)-2-iodobutance reacts with NAI in acetone to form `(+-)`. 2-iodobutane, which leads to reacemisation. Thus the solution become optically inactive.

Each `S_(N)2` attack on (+)-2-iodobutane by `I^(THETA)` occurs with inversion of CONFIGURATION resulting in the formation of (-)-2-iodobutance. As the concentration of the (-)-enantiomer in the reaction MIXTURE increases, its tendency to reacts with `I^(Theta)` forming a(+)-enantimer increases. At a certain time, the mixture contains equimolar amounts of (+) and (-) -2- iodobutane. Since both the enantiomers react with `I^(Theta)` at the same rate (because the ACTIVATION energy is the same), their composition remains unchanged. As the rotation caused by the molecules of one enantiomer is exactly cancelled by equal and opposite rotation caused by the same number of molecules of the other enantiomer, the mixture is optically inactive.
Discussion
93902.

A solution of (-) -1-chloro-1-phenylethane in toluene racemises slowly in the presence of a small amount of SbCl_(5), due to the formation of :

Answer»

carbonion
CARBENE
free-radical
carbocation.

Answer :D
Discussion
93903.

(+) - 2 - chloro - 2 - phenylethane in toluene racemises slowly in the presence of small amount of SbCI_(5), due of the formation of-

Answer»

carbanion
carbene
free - radical
CARBOCATION

Solution :`SbCI_(5)` abstracts `CI^(-)` ion from (+) - 2 - chloro - 2 - phenyl - ETHANE & forms a planar carbocation. Now, the NUCLEOPHILE `(CI^(-))` can attack this carbocation from SIDE of the plane thereby causing racemisation of the compound.
Discussion
93904.

+2 and +3 oxidation state is stable in which of the following respectively

Answer»

`EU, LU`
`CE, Lu`
`Eu, ND `
`Ce, Eu`

ANSWER :A
Discussion
93905.

._(13)Al^(27) is a stable isotope. ._(13)Al^(29) is expected to disintegrate by

Answer»

`alpha` EMISSION
`_(-1)^(0) beta` emission
Positron emission
Proton emission

Solution :Since `._(13)^(27) Al` is stable isotope , `._(13)^(29)Al`has `(n)/(P)` RATIO higher than required, it will disintegrate by `beta^(-)` emission and `(n)/(P)` ratio will decrease.
`._(13)^(29)Al rarr ._(14) si^(29)+._(-1)E^(0)`
Discussion
93906.

(+)-1-chloro-1-phenylethane is toluene racemises slowly in the presence of small amount of SbCl_(5) due to the formation of:

Answer»

carbocation
carbene
free radical
carbonion

Solution :A carbocation INTERMEDIATE is FORMED in the presence of `SbCl_(5)`. As the carbocation is PLANAR, it can be attacked by `SbCl_(6)^(-)` to give two enantiomers of 1-chlorophenylethane. The enentiomers lead to RACEMISATION and give a racemic mixture.
`CH_(3)-underset(H)underset(|)overset(Cl)overset(|)(C)-C_(6)H_(5)overset(-Cl^(-))toCH_(3)-underset(("Intermediate"))overset(o+)(C)H-C_(6)H_(5)`
Discussion