Which gas is released when acid reacts with metal?

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Under what soil condition do you think a farmer would treat the soil of his fields with quick lime $(CaO)$,slaked lime $(Ca(OH)_2)$,or chalk $(CaCO_3)$?

Which of the following are present in a dilute aqueous solution of hydrochloric acid?

Which ions are produced when caustic soda undergoes ionization in water?

Write true or false for the following statement:
The process of dissolving an acid or a base in water is a highly exothermic process.