At the lowest rate at room temperature, the reaction proceeds between: a. iron and oxygen b. calcium carbonate

At the lowest rate at room temperature, the reaction proceeds between: a. iron and oxygen b. calcium carbonate and hydrochloric acid c. sodium hydroxide solution and sulfuric acid d. copper sulfate solution and sodium hydroxide solution

The reaction between a) iron and oxygen proceeds at the slowest rate at room temperature.

The rate of a chemical reaction depends on the nature and state of aggregation of the reacting substances. Ion exchange reactions in solution occur almost instantly. Substances in different states of aggregation react more slowly.

Under points c) and d), ion exchange reactions in solution are indicated.

Under point b) – the reaction of ion exchange CaCO3 (s) and HCl (g).

The reaction between the solid (Fe) and the gaseous substance (O2) is slower (the contact area is small). The rate of reaction will be affected by the degree of grinding of the iron.