What are elastomers? Give examples of elastomers.

$A$ $2 \,m$ long rod of radius $1 \,cm$ which is fixed from one end is given a twist of $0.8$ radians. The shear strain developed will be

Match the details of Column-$II$ with the given information in Column-$I$ appropriately.

Column-$I$	Column-$II$
$(a)$ Stress is proportional to strain.	$(i)$ Elastic limit
$(b)$ When the load on the wire is removed, the body regains its original dimension.	$(ii)$ Limit of proportionality
	$(iii)$ Plastic deformation

Below are two statements. One is labeled as Assertion $(A)$ and the other as Reason $(R).$
Assertion $(A):$ The property of an object that allows it to regain its original shape after the external force applied to it is removed is called elasticity.
Reason $(R):$ The restoring force depends on the intermolecular and interatomic forces in a solid.
In the context of the above statements,choose the most appropriate answer from the options given below:

$A$ wire of diameter $1\, mm$ breaks under a tension of $1000\, N.$ Another wire,of the same material as that of the first one,but of diameter $2\, mm$ breaks under a tension of ...... $N$.

Two identical solid balls,one of ivory and the other of wet-clay,are dropped from the same height on the floor. Which one will rise to a greater height after striking the floor and why?