directions: classify the following as being a physical (p) or chemical (c) change.\n1. sodium hydroxide…

Brief Explanations:

1. Sodium hydroxide dissolving in water is a physical change as no new substances are formed chemically, just a dissolution process.
2. Hydrochloric acid reacting with potassium hydroxide to produce a salt, water, and heat is a chemical change as new substances are formed through a chemical reaction.
3. Slicing a sodium pellet is a physical change as it only changes the physical form and no new substances are created.
4. Water changing to steam upon heating is a physical change as it is a phase - change and no new chemical substances are formed.
5. Decomposition of potassium chlorate to potassium chloride and oxygen gas is a chemical change as new substances are formed.
6. Iron rusting is a chemical change as iron reacts with oxygen and moisture to form iron oxide (rust), a new substance.
7. Sodium reacting with water to produce hydrogen gas and catch fire is a chemical change due to the formation of new substances.
8. Evaporation of alcohol is a physical change as it is a phase - change from liquid to gas without forming new chemical substances.
9. Ice melting is a physical change as it is a phase - change from solid to liquid without a chemical reaction.
10. Milk souring is a chemical change as bacteria cause chemical reactions to produce acidic substances.
11. Sugar dissolving in water is a physical change as it is a dissolution process with no new chemical substances formed.
12. Wood rotting is a chemical change as microorganisms cause chemical reactions to break down the wood.
13. Pancakes cooking on a griddle is a chemical change as heat causes chemical reactions in the batter.
14. Grass growing in a lawn is a chemical change as it involves complex biochemical reactions.
15. Inflating a tire with air is a physical change as it only changes the volume and pressure of the air in the tire, no new substances are formed.
16. Food digestion in the stomach is a chemical change as enzymes break down food into new substances.
17. Water being absorbed by a paper towel is a physical change as it is a physical adsorption process with no new chemical substances formed.
18. Grinding coffee beans is a physical change as it only changes the physical form of the beans.
19. Shredding homework is a physical change as it only changes the physical form of the paper.
20. Baking chocolate - chip cookies is a chemical change as heat causes chemical reactions in the dough.

Answer:

1. P
2. C
3. P
4. P
5. C
6. C
7. C
8. P
9. P
10. C
11. P
12. C
13. C
14. C
15. P
16. C
17. P
18. P
19. P
20. C