Question

: Name a metal which reacts with steam?
A.Sodium
B.Potassium
C.Lithium
D.Magnesium

Answer 1

Hint: The metal which is generally less reactive reacts with the stream instead of normal water. The element belongs to alkaline earth metal.

Complete step by step answer:
-Generally the reactive metals react readily with normal water or cold water to form their respective oxides and liberate hydrogen gas. The less reactive metals such as aluminium, zinc, iron and magnesium do not react with normal water instead they react with steam. Steam has a higher energy than water because it is in a gaseous state and hence provides the activation energy for the formation of required products which is not needed in case of the more reactive metals.
-Sodium, potassium and lithium all belong to the group 1 of the modern periodic table. They are the most active elements and readily react with water. Sodium even gives an explosive reaction when it reacts with water. The reaction mixture sometimes catches fire due to the presence of hydrogen which is combustible in nature. That is why sodium is stored in the kerosene because it reacts with the moisture in the air.
-Magnesium is the metal that reacts with steam to produce magnesium hydroxide and hydrogen gas. We can write the reaction as follow:
\[{\text{Mg}} + {{\text{H}}_2}{\text{O}} \to {\text{MgO}} + {{\text{H}}_2}\]

Hence option D is correct.

Note:
Magnesium belongs to the group 2 of the modern periodic table. It is also known as alkaline earth metal because their oxides and hydroxide are basic in nature or form a basic solution in water (alkali) and they are mainly found in earth crust. The atomic number of magnesium is 12. Its oxide is also used as an antacid.