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Moderate

Predicting Reactivity and Ionization Energy

APCHEM-YSLVNG

Alkali metals ($M$, group 1) react with water to form an aqueous alkali metal hydroxide ($MOH$) and hydrogen gas as shown by the general equation below:

$$2 M(s) + 2 { H }_{ 2 }{ O }_{ } \rightarrow 2 MOH(aq) + {H}_{2}(g)$$

Which of the following elements would react MOST rapidly with water?

A

Lithium ($Li$).

B

Sodium ($Na$).

C

Potassium ($K$).

D

Rubidium ($Rb$).