Correct statement among the following regarding conductivity in solids is -

1.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>\gg <mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}$

2.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>\ll <mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}$

3.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>,<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}<mspace\; width="1em"></mspace>><mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>\mathrm{zero}$

4.  ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}<mspace\; width="1em"></mspace>><mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace>\ne <mspace\; width="1em"></mspace>\mathrm{zero}$