The breaking stress of a wire depends upon

What is stress? Write its unit and dimensional formula.

Identify whether the following statements are True or False:
$(a)$ If a body breaks immediately after the elastic limit,then this body is known as ......
$(b)$ An elastic body which can be stretched to cause large strains is called ......

Define plastic deformation and tensile strength.

$A$ metal block of mass $m$ is suspended from a rigid support through a metal wire of diameter $14\,mm$. The tensile stress developed in the wire under equilibrium state is $7 \times 10^5\,N m^{-2}$. The value of mass $m$ is $......kg$.
(Take,$g = 9.8\,m s^{-2}$ and $\pi = \frac{22}{7}$)

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: