Equal weights of Shahabad tile pieces and Shahabad tile powder are each treated with dilute HCl. CO$_2$ effervescence appears faster with the powder. This shows that the rate of reaction increases when:

1. The only difference between the two test tubes is the particle size of the tile. 2. The powder, having smaller particles, gives faster effervescence than the pieces. 3. Hence smaller reactant particle size means a higher rate of reaction. 4. Larger particles would react slower, and dilution or lower temperature would slow reactions, so those options are wrong. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 3 "Chemical Reactions and Equations", p.49_