Use the data in Table 12.2 to answer the following −Table 12.2 Electrical resistivity of some substances at 20°C − Material Resistivity (Ω m) Conductors Silver 1.60 × 10−8 Copper 1.62 × 10−8 Aluminium 2.63 × 10−8 Tungsten 5.20 × 10−8 Nickel 6.84 × 10−8 Iron 10.0 × 10−8 Chromium 12.9 × 10−8 Mercury 94.0 × 10−8 Manganese 1.84 × 10−6 Constantan (alloy of Cu and Ni) 49 × 10−6 Alloys Manganin (alloy of Cu, Mn and Ni) 44 × 10−6 Nichrome (alloy of Ni, Cr, Mn and Fe) 100 × 10−6 Glass 1010 − 1014 Insulators Hard rubber 1013 − 1016 Ebonite 1015 − 1017 Diamond 1012 − 1013 Paper (dry) 1012 (a) Which among iron and mercury is a better conductor?(b) Which material is the best conductor?