Liquid mercury at \(0.25 \mathrm{~kg} / \mathrm{s}\) is to be heated from 325 to \(375 \mathrm{~K}\) by passing it through a \(25-\mathrm{mm}\)-diameter tube whose surface is maintained at \(400 \mathrm{~K}\). Calculate the required tube length by using an appropriate liquid metal convection heat transfer correlation. Compare your result with that which would have been obtained by using a correlation appropriate for \(\operatorname{Pr} \gtrsim 0.7\).