Resistance and Resistivity

A metal wire of cross-sectional area $$0.5\,\mathrm{mm^2}$$ and length $$100\,\mathrm{m}$$ is connected across a battery of e.m.f. $$2\,\mathrm{V}$$ and internal resistance $$1\,\Omega$$. The density, atomic mass and electrical conductivity of the metal are $$6.35\times 10^{3}\,\mathrm{kg\,m^{-3}}$$, $$63.5\,\mathrm{gm/mole}$$ and $$2\times 10^{8}\,\mathrm{mho\,m^{-1}}$$, respectively. Assuming one conduction electron per atom of the metal, the drift velocity (in $$\mathrm{mm\,s^{-1}}$$) of the electrons in the wire is:

[Take Avogadro's number as $$6\times 10^{23}$$ and charge of the electron as $$1.6\times 10^{-19}\,\mathrm{C}$$.]