Answer: (a) Nature of the reactants, size of the particles (surface area), concentration, temperature and catalyst; (b) explained below for temperature.
(a) The rate of a reaction depends on: the nature of the reacting substances, the size of the particles (more finely divided reactants react faster), the concentration of the reactants, the temperature, and the presence of a catalyst.
(b) Temperature: at a higher temperature the molecules move faster and a larger fraction of them has enough energy to break the old bonds, so more collisions are effective and the reaction becomes faster. For example, food cooks faster at a higher flame temperature, and magnesium burns faster in oxygen when heated.