If the same amount of solid sodium (na) is used in each reaction, which shape will increase the reaction rate the most?

a. the reaction rate is highest when 2 cm2 blocks of sodium are used.
b. the reaction rate is highest when sodium powder is used.
c. the reaction rate is highest when 3 cm2 blocks of sodium are used.
d. the reaction rate is highest when strips of sodium are used.

(B.) The reaction rate is highest when sodium powder is used.

Explanation:

Five factors that affect the rate of reactions are : Temperature, concentration, nature of catalyst, chemical nature of reactants and  nature of subdivision of particles (heavier size versus smaller or powdered particles).

Nature of subdivision of particles :

Since reactions occur at the boundary between two phases therefore tyhe rate of reaction depends on surface contact available between them. A powdered particle has generally more surface area than the particle in solid form.