What type of oxide is $H_{2}O$?

On adding dilute hydrochloric acid to copper oxide powder,the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution.

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

Which gas is released when acid reacts with metal carbonate or metal hydrogen carbonate?

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

Which of the following acids is called 'the king of chemicals'?