Question

Methylpropylamine is optically inactive because
i) It is tetrahedral
ii) Its molecule is superimposable on its mirror image.
iii) The enantiomers are rapidly interconverted
iv) The nitrogen is $s{p^2}$ hybridized
Which of the above statements is(are) true?
A. Only (i)
B. Only (ii)
C. (i) and (iii)
D. All the four

Answer 1

At first we must know what Methylpropyl amine and what type of structure it has. We should also know that what does optically inactive mean. Now we can find that it is optically active or inactive by understanding the nitrogen atom present in the amine. Once we find out the correct explanation and what is happening in the compound we can choose the correct option

Complete answer:
Step1. Methylpropyl amine is a chemical compound with the amine function group in it. We are given that the Methylpropyl amine is optically inactive.
Step2. When it is said that a compound is optically inactive, it means that it does not rotate around the plane of polarized light.
Step3: The nitrogen present in it has $s{p^3}$ tetrahedral structure. It also has a nitrogen lone pair in $s{p^3}$ orbital. The tetrahedral structures of amines are in equilibrium. When we look into isomerism, we found that these structures are enantiomers. Now the anime enantiomers have equal and opposite optical activity. So when mixture is in the equilibrium of $1:1$, it is racemic and it becomes optically inactive. The enantiomers rapidly interconvert.

Hence, the correct option is B.

Note: We have seen isomerism above. Isomers are those compounds which have the same chemical formula but they represent different chemical and physical properties. It happens because of alignment of atoms in free space or the difference in bond length. It was first observed in the $1827$ in $AgCNO$. It is of two types. One is structural and other is stereoisomerism.