Question

3. Which compound is formed when the powder obtained reacts with water?

Answer 1

The compound formed when the powder obtained reacts with water is Magnesium hydroxide ($\[Mg{(OH)_2}\]$).

Explanation:

• When magnesium ribbon is burnt in the air, it reacts with oxygen to form magnesium oxide.
• It is obtained as white ash or powder.
• The reaction is given as: $\[2Mg + {O_2} \to 2MgO\]$
• When this white powder (MgO) is treated with water, it undergoes a combination reaction to form magnesium hydroxide.
• The reaction is given as:

        $\[MgO + {H_2}O \to Mg{(OH)_2}\]$

• Thus, the compound formed is magnesium hydroxide ($\[Mg{(OH)_2}\]$).