This is the boss. No calculator — today $c = 4.2\ \mathrm{J/(g\cdot^{\circ}C)}$, the round number every chemist keeps for mental work, and every value is chosen to fit in your head. One pellet, one long problem, and every answer feeds the next: grams to moles, moles to kilojoules, kilojoules to joules, joules to a temperature rise — and then the line that actually matters, whether the run passes its specification.

Write each line down as you go. A slip in line one does not stay in line one; it walks all the way to the verdict wearing a straight face. And note what the last question asks for: not a number, a decision. Every real report ends that way. 5★ under par here is the chapter crown. Clock in.