Question

A solution X turns blue litmus red and another solution Y turns red litmus blue, when solutions X and Y are mixed the products will be ___ and ___, if a piece of magnesium were put into solution X___ gas, would be evolved.

• A. Salt and Water
• B. Hydrogen

Answer 1

• Given solution X is acid which contains Hydronium ions. Acids always turns blue litmus red.
• Given solution Y is basic which contains Hydroxyl ions. Basic solution always turns red litmus blue.
• Always when an acid reacts with alkali(base) the products will be salt and water.

Example: HCl(aq) + NaOH(aq) ⇢ NaCl (salt) + H₂O(aq)

• Acid salt partly replaced Hydrogen gas when reacts with a metal, Since magnesium is a metal compound it replaces hydrogen gas.

Mg(s) + 2HCl(aq) ⇢ MgCl₂(aq) + H₂(g)