Which general equation represents the neutralisation of a dilute acid with an alkali to form a metal salt and water?

• A. dilute acid + alkali → metal salt + water
• B. acid + metal → salt + hydrogen
• C. alkali + metal oxide → salt + water
• D. acid + base → salt + hydrogen gas

Answer: (A)

Neutralisation happens when an acid reacts with a base (or alkali) in water. The H+ from the acid combines with the OH− from the alkali to form water, and the remaining ions pair up to form a salt. Because the alkali supplies metal ions in solution, the salt formed is a metal salt. That’s why the general equation is acid + alkali → metal salt + water. For example, HCl (acid) + NaOH (alkali) → NaCl (metal salt) + H2O. The other ideas describe different reactions: metals reacting with acids release hydrogen gas, and reactions with metal oxides involve different partners or products, not the simple acid–alkali neutralisation that produces water.