Direction (Q. Nos. 1 - 6) This section contains 6 multiple choice questions. Each question has four
choices (a), (b), (c) and (d), out of which ONLY ONE option is correct.
A pure enantiomer with molecular formula C6H13OBr, when reacted with PBr3, an achiral product C6H12Br2 is obtained that has no chiral carbon. The compound which satisfy this condition could be (no bond to chiral carbon is broken during the reaction)
Optical rotation of a newly synthesised chiral compound is found to be +60°. Which of the following experiment can be performed to establish that optical rotation is not actually -300°?
How many stereoisomers exist for the compound 4-(1- propenyl) cyclohexane ?
The correct answer is option C
1,4-Dimethylcyclohexane consists of two diastereomeric stereoisomers, although, according to the n2 rule, four stereoisomers should be expected due to the fact that 1,4-dimethylcyclohexane contains two asymmetric carbons.
what is incorrect regarding cis -1, 3-dibromo - trans-2,4-dichlorocyclobutane ?
consider the following zonolysis reaction
The correct statement about the above product formed is
A hydrocarbon with molecular formula C6H8 is chiral but upon catalytic hydrogenation gives achiral hydrocarbon of molar mass 86. Which of the following could be the starting compound?
Direction (Q. Nos. 7 and 14) This section contains 8 questions. when worked out will result in an integer from 0 to 9 (both inclusive)
How many stereoisomers exist in the compound 1-methyl-3-(1-propenyl) cyclohexane ?
The correct answer is 8
Carbon no.1 is chiral carbon so H Show 2 optical isomers
Carbon no.3 is also chiral carbon
Hence, shows two optical isomers
Carbon 1 & carbon 3 shows G.I. due to 1 stereocenter
Propenyl shows 2 G.I.
Total 8 isomers are shown here.
If 3-ethylpentane is subjected to free radical chlorination, how many different monochlorination product would be produced?
How many chiral carbons are present in the compound shown below ?
All the highlighted position are chiral centres.
How many pairs of diastereomers can be made for the compound shown below ?
In principle, how many different monocarboxylic isomers, on decarboxylation with soda lime, can give the same 3-methyl pentane?
How many isomers are possible for C3H2Cl2 ?
There are 9 isomers of C3H2Cl2.
How many stereoisomers are possible for 5-chloro-2,3hexadiene ?
The correct answer is 4
2-chloro-4-methyl hex-2-ene has a double bond, so has two geometrical isomers.
It has one asymmetric carbon atom.
So, it has 2 optical isomers
So, total isomers =2+2=4
How many different monoenols exist for 4-methyl-2,5-heptanedione ?
Correct answer is 6
Because it can exist in the keto form and a indol form and it was isomerization taking place during
chromatography which causes the G c peak to diffuse
Direction (Q. Nos. 15-18) This sectionis based on statement I and Statement II. Select the correct answer from the code given below
Statement I A racemic mixture is optically inactive.
Statement II Racemic mixture contain a pair of enantiomers.
The correct answer is Option A.
Racemic mixture is an equimolecular mixture of enantiomeric pairs. The rotation caused by the molecules of one enantiomer is cancelled by the rotation caused by the molecules of another enantiomer.
Statement I Cis-1,4-dichlorocyclobutane is optically inactive.
Statement II It possesses plane of symmetry.
Statement I 2,3-pentadiene is enantiomeric.
Statement II Enantiomers of 2,3-pentadiene are non-interconvertible due to very large rotational barrier.
Statement I : The Compound shown below is optically inactive.
Statement II Compound shown above possesses axis of rotation.
Statement I Decreasing length of sample tube, while keeping everything else intact, decreases the magnitude of optical rotation.
Statement II Decreasing length of sample tube decreases the contribution of sample tube material to the total optical rotation.
Direction (Q. Nos. 20-21) Choice the correct combination of elements and column I and coloumn II are given as option (a), (b), (c) and (d), out of which ONE option is correct.
Consider the molecules in Column I and match them with their stereochemical properties from Column II
Match the stereochemical terms in column I with their description in column II