**Category:** Inorganic Chemistry  
**Subtype:** Chemical Reactions, Stoichiometry  
**Problem Description:** This problem involves the dissolution of a mixture of metals and metal oxides in water, leading to the production of gas and a solution. It also includes the absorption of carbon dioxide (CO₂) and the formation of precipitates, requiring calculations to determine the mass of the original mixture (m). The problem requires understanding of gas laws, stoichiometry, and precipitation reactions.