Is it possible to double the length of a metallic wire by applying force over it?

The breaking stress of aluminium is $7.5 \times 10^7 \,N m^{-2}$. The greatest length of aluminium wire that can hang vertically without breaking is ......... $\times 10^3 \,m$ (Density of aluminium is $2.7 \times 10^3 \,kg m^{-3}$ and $g = 9.8 \,m s^{-2}$)

Why do rail tracks have an '$I$-shaped' girder?

When a load of $80 \,N$ is suspended from a string,its length is $101 \,mm$. If a load of $100 \,N$ is suspended,its length is $102 \,mm$. If a load of $160 \,N$ is suspended from it,then the length of the string is (Assume the area of cross-section is unchanged). (in $\,cm$)

Two equal and opposite forces are exerted on a bar (rod) as shown in the figure. The plane $PQ$ makes an angle $\theta$ with the cross-section $PR$ (having area $a$). Find the tensile stress on the plane $PQ$.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Steel is used in the construction of buildings and bridges.
Reason $R$: Steel is more elastic and its elastic limit is high.
In the light of the above statements,choose the most appropriate answer from the options given below: