Question

One would come across the terms isotactic, syndiotactic and atactic in connection with the chemistry of-----.
A. Polymers
B. Dyes
C. Crystals
D. Textiles

Answer 1

To determine the answer we should know the meaning of the given terms. The given terms define the arrangement or position of substituents. When one type of molecule or may be two types of molecules joins again and again and forms a long chain. The chain is known as backbone. In isotactic, all substituents are present on the same side of the chain. In syndiotactic, positions of substituents are alternate. In actactic, the position of substituent is random.

Complete step-by-step answer:
The terms isotactic, syndiotactic and atactic, all define the arrangements of a group or we can say the stereochemistry of adjacent chiral centres in a long chain formed by the repetition of one or two molecules.

All these terms are defined as follows:
-Isotactic: When all substituents are present on the same side of the main chain which is known as backbone, the arrangement is known as isotactic.
-Syndiotactic: When arrangement of substituents is alternate, the arrangement is known as syndiotactic. If the substituents at one chiral centre will be towards us then the substitutes at the next chiral centre will be far from us. Again the substitutes at the next chiral centre will be towards us and so, on.
-Atactic: When we can specify a fixed arrangement of substituents at the backbone then the arrangement is known as astatic. All the substituents are present randomly.

When a large number of the same type of two different type molecules join in a specific manner to form a long structure, the structure is known as a polymer.All the terms, isotactic, syndiotactic and atactic, define the arrangement of substituents at the polymer chain. So, one would come across the terms isotactic, syndiotactic and atactic in connection with the chemistry of polymers.

Therefore, option (A) Polymers, is correct.

Note: Based on the arrangement of substituents, the polymers are of three types, isotactic, syndiotactic and atactic. Based on the type of polymeric units the polymer is of two types, homopolymer and copolymer. When only one type of repeating unit is present in a polymer the polymer is known as a homopolymer. When more than one type of repeating unit is present in a polymer the polymer is known as copolymer. The units which repeat are known as repeating units or monomers.