Question

1. how do you know whether or not a new substance was produced in these reactions?

Explanation:

In a chemical reaction, signs like color change, gas evolution (bubbles), precipitate formation (solid from solution), temperature change (exothermic/endothermic), or odor change indicate new substance formation. These are chemical properties changes. Physical changes (e.g., state change) don't show these.

Answer:

Look for signs like color change, gas evolution, precipitate formation, temperature change, or odor change. These suggest a new substance is formed as they are chemical property alterations.