Question

Arrange the following metals in the decreasing order of their reactivity.

• A. $K$
• B. $Na$
• C. $Ca$
• D. $Mg$
• E. $Fe$

Answer 1

Metals are arranged in the decreasing order of their reactivities, and this table is known as the reactivity series.

$K$ and $N$a react the most vigorously with water, reacting violently even with cold water to release $H_2$ gas, followed by $Ca$, which reacts with cold water, but with less vigour.

$Mg$ barely reacts with cold water, but reacts with warm water.

$Fe$ reacts only with steam.

This trend points to a following order of reactivity -
$K>Na>Ca>Mg>Fe$.