What is the resistivity of a perfect conductor?

Wires $A$ and $B$ have resistivities $\rho_A$ and $\rho_B$,where $\rho_B = 2 \rho_A$,and have lengths $l_A$ and $l_B$. If the diameter of wire $B$ is twice that of $A$ and the two wires have the same resistance,then the ratio $\frac{l_B}{l_A}$ is:

$A$ wire is stretched to increase its length by $2\%$,then the percentage change in its resistance is . . . . . . . (in $\%$)

The resistance of a conductor increases with:

As the temperature increases,the electrical resistance:

The resistance of a wire is $10\,\Omega$. Its length is increased by $10\%$ by stretching. The new resistance will now be .......... $\Omega$.