Explanation:
Mg is solid metal.
In general, the rate of a reaction is increased by:
Increasing the concentration of a reactant in solution.
Increasing the surface area of a solid reactant. The more surface area, the more frequency of collisions.
Increasing the temperature of the reaction system.
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According to this, grinding the Mg metal into a fine powder will increase the rate of the reaction.
Answer: grinding the Mg metal into a fine powder.
