Question

Of the three metals X, Y and Z, X reacts with cold water, Y with hot water and Z with steam only. Increasing order of reactivity with their identity is:

• A. $Na>Mg>Fe$
• B. $Mg>Na>Fe$
• C. $Na>Fe>Mg$
• D. $Na=Fe=Mg$

Answer 1

The correct option is A $Na>Mg>Fe$

Alkali metals are the most reactive metals, therefore X is an alkali metal. (e.g: $Na$ or $K$)
Alkaline Earth metals are most reactive than other metals except alkali metals, therefore Y is an alkaline earth metal. (e.g: $Mg$ or $Ca$)
Z is any other metal less reactive than alkali and alkaline earth metals but more active than hydrogen. (e.g: $Fe$)
The increasing reactivity series can be written as: X > Y > Z.