Conductivity increases in the order of

Why are alloys used for making standard resistance coils?

In order to increase the resistance of a given wire of uniform cross-section to four times its value,a fraction of its length is stretched uniformly until the full length of the wire becomes $\frac{3}{2}$ times the original length. What is the value of this fraction?

The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be..... $\%$.

With an increase in temperature,the resistivity of a conductor ........ and the resistivity of a semiconductor ....... .

In the following,$I$ refers to current and other symbols have their usual meaning. Choose the option that corresponds to the dimensions of electrical conductivity.