The reaction B → products is monitored at 35 °C, giving the following concentrations of B: 0 s — 1.20 M, 290 s — 0.68 M, 300 s — 0.66 M, 310 s — 0.64 M.
Calculate (i) the instantaneous rate of disappearance of B at 300 s and (ii) the average rate of disappearance of B over the interval 0–300 s. Provide both answers with units.