Question

Cellulose, proteins and starch are classified as:
A.Natural polymer
B.Aldehyde
C.Esters
D.Synthetic polymer

Answer 1

Cellulose, proteins and starch are the examples of polymers because they are formed by the chains of one or more compounds. For example: proteins is the polymer of amino acids.

Complete step by step solution:
We know that polymers are materials made of long, repeating chains of molecules. The materials have unique properties, depending on the type of molecules being bonded and how they are bonded.
Polymers are of two types based on their occurrence: natural polymer and synthetic polymer.
Natural polymer: Those polymers which are found in nature i.e. found in animals or plants, are known as natural polymers. For example: cellulose, starch, proteins, silk, wood,etc.
Synthetic polymers: Those polymers which are not found in nature are man-made. They are made in laboratories. For example: Bakelite, Buna-s, Buns-n, etc.
Polymers are classified into four categories :
1.Thermoplastic
2.Thermosetting
3.Fibres
4.Elastomer
We can define all these four types of polymer as follows:
Elastomers: These are the molecules which have the weak intermolecular forces.They are very elastic.
Examples are: Natural rubber, neoprene, Buna-S
Thermoplastic: All the plastic material which can be softened and melted by heating but they set again when cool, are called thermoplastic polymers.
Examples are: Polyethylene, Polypropylene, polyvinyl chloride
Thermosetting: They are generally a liquid at room temperature which hardens irreversibly on heating.
Examples are: Polyurethane , Bakelite
Fibres: These are the polymers which have the strong intermolecular force between the chains.
Examples are: Polyvinyl chloride, phenol formaldehyde.

Hence option A i.e. Cellulose, proteins and starch are classified as natural polymer, is correct

Note:
The order of molecular strength (the force of attraction between the molecules) in these different types of polymers is:
Elastomers $<$ Thermoplastic $<$ Fibres $<$ Thermosetting.