Some materi

a) The materials are required for the preparation of more CO₂ in less time are Marble powder and concentrated HCl because if we take marble powder then the surface area increases and the number of molecules undergoing effective collisions also increases. So, the rate of reaction will increase. And if we take concentrated HCl then the number of molecules per unit volume increases and the number of effective collisions also increases. So, the rate of reaction will increase.

b) CaCO₃ (s)+ 2HCl (aq) CaCl₂ (aq) + H₂O (l) + CO₂ (g)

Note- Carbonates on reaction with dilute HCl produces metal chloride, water and CO2 gas.