Same tension is applied to the following four wires made of same material. The elongation is longest in

Young's modulus of a wire is $$2 \times 10^{11} \mathrm{Nm}^{-2}$$. If an external stretching force of $$2 \times 10^{11} \mathrm{~N}$$ is applied to a wire of length $$L$$. The final length of the wire is (cross-section = unity)

The Young's modulus of a rubber string of length $$12 \mathrm{~cm}$$ and density $$1.5 ~\mathrm{kgm}^{-3}$$ is $$5 \times 10^8 ~\mathrm{Nm}^{-2}$$. When this string is suspended vertically, the increase in its length due to its own weight is (Take, $$g=10 \mathrm{~ms}^{-2}$$ )