Question

Most reactive metal is:
A. $Na$
B. $Mg$
C. $Cu$
D. $Au$

Answer 1

In order of the question, to know which one is more reactive, we have to go through the reactivity series or activity series of common metals and also have to know the reason behind why the metals are more reactive than others.

Complete answer: In the given optional metals, Sodium $Na$ is the most reactive among all the given metals.According to the reactivity or activity series, the order of reactive metals are: $Na$ , $Mg$ , $Cu$ and $Au$ . The main reasons of why Sodium is more reactive than other given metals are as follows:
$*$ According to the reactivity series, the metals at the top of the series are powerful reducing agents since they are easily oxidised. So, Sodium $Na$ is easily oxidised among all given metals. $Na$ also corrodes very easily.
$*$ While traversing down the series, the reducing ability of the metals grows weaker or we can say that the reducing ability of $Na$ is weakest among all the given four metals.
$*$ While traversing down the series, the electro-positivity of the elements reduces or we can say that the electro-positivity of $Na$ is reduced among all the given four metals.
$*$ $Na$ and $Mg$ liberate ${H_2}$ gas upon reacting with dilute $HCl$ or ${H_2}S{O_4}$ . As both the elements are found above the Hydrogen in the reactivity series.
$*$ Higher ranking metals require greater amounts of energy for their isolation from ores and other compounds. That means Sodium requires greater amounts of energy for their isolation from ores and other compounds among all the four metals.
$*$ The electron donating ability of the Sodium is also reduced.

Hence, the correct option is (A.) $Na$ .

Note: The elements in the periodic table known as the transition metals are much less reactive, and metals such as gold and platinum endorse the bottom of the list, exhibiting less in the way of chemical reaction with any ordinary reagents.