Question

which of the following observations would indicate a chemical change has happened? select all correct answers. select all correct options folded in half a solid precipitate forms heat energy is released a gas is produced breaks into smaller pieces

Explanation:

• A solid precipitate forming indicates new substances (chemical change).
• Heat energy released (exothermic reaction) shows chemical bonds breaking/forming (chemical change).
• Gas production implies new gaseous substances (chemical change).
• Folding in half and breaking into smaller pieces are physical changes (no new substances).

Answer:

• a solid precipitate forms
• heat energy is released
• a gas is produced