Hf has a bond length of 92 pm. calculate the moment of inertia of the molecule and hence the energy required to excite it from the j = 0 to the j = 1 energy level. (a) at what temperature does this energy equal the thermal energy kt? (b) at what wavelength could this excitation be induced using electromagnetic radiation?

100 grams of molten lead (600°c) is used to make musket balls. if the lead shot is allowed to cool to room temperature (21°c), what is the change in entropy (in j/k) of the lead? (for the specific heat of molten and solid lead use 1.29 j/g⋅°c; the latent heat of fusion and the melting point of lead are 2.45 × 104 j/kg and 327°c, respectively.)