1. For the metallic element with atomic number 29, calculate the number of atoms in a critically sized nucleus at the homogeneous nucleation temperature. Hint: You will need the lattice parameter of this element, which can be found in Appendix A of your textbook.

2. A 3.9-cm-diameter sphere solidifies in 915 s. Calculate the solidification time for a 0.5 by 11 by 15 cm plate cast under the same conditions. Assume that n=2. Give your answer in seconds.