Which graph shows correctly the temperature (T). dependence of resistivity $(\rho)$ of a semiconductor?

Two uniform wires of same material are vibrating under the same tension. If the $1^{\text {st }}$ overtone of $1^{\text {st }}$ wire is equal to the $2^{\text {nd }}$ overtone of $2^{\text {nd }}$ wire and radius of $1^{\text {st }}$ wire is twice the radius of $2^{\text {nd }}$ wire, the ratio of length of $1^{\text {st }}$ wire to that $2^{\text {nd }}$ wire is

A liquid drop of volume V is placed on the surface of glass plate. Then another glass plate is placed on it such that liquid forms a thin layer of area A between the surfaces of two plates. To separate the plates a force F has to be applied normal to the surfaces. The surface tension of the liquid is