Questions

Terylene and nylon are synthetic fibres produced by a process of polymerisation. Terylene is a polyester and nylon, a poyamide.

Silk is purely a natural product obtained from silk worms.

Rayon is a man-made material which consists of purified cellulose in the form of long fibres. Cellulose occurs in the cell wall of plants. Rayon fibre is chemically identical to cotton but has a shine like silk. Since it is  basically derived from a natural source (cellulose) it is called a regenerated fibre.

Atomic  number  is  the  fundamental properties  of  an  element.  Every atom  is  identified  by  its  unique atomic  number.  Atomic  number  is equal  to  the  number  of  protons present in an atom of the element.

Refractorymeans unmanageablewhich is nearly opposite to manageable.Refreshing means revivifyingBurdensome means troublesomePrivileged means advantage

In the year 1620, Plymouth colony was established by separatists.

The rule followed here is

7 + 3 - 4 = 6

Similarly,

4 + 2 - 2 = 4

9 + 5 - 4 = 10

Hence, the missing numbers are 4 & 10.