Question

part c: true (t) or false (f)

1. changing the size and shapes of pieces of wood would be a chemical change.
2. in a physical change, the makeup of matter is changed.
3. evaporation occurs when liquid water changes into a gas.
4. evaporation is a physical change.
5. burning wood is a physical change.
6. combining hydrogen and oxygen to make water is a physical change.
7. breaking up concrete is a physical change.
8. sand being washed out to sea from the beach is a chemical change.
9. when ice cream melts, a chemical change occurs.
10. acid rain damaging a marble statue is a physical change.
11. in a fireworks show, the fireworks explode giving off heat and light.

Explanation:

To solve these true - false questions, we analyze each one based on the definitions of physical and chemical changes. A physical change is a change in the form or appearance of a substance without changing its chemical composition. A chemical change involves a change in the chemical composition of a substance, often accompanied by the formation of new substances.

Question 1

• Explanation: Changing the size and shape of wood only alters its physical appearance. The chemical composition of the wood remains the same. So this is a physical change, not a chemical change.
• Answer: F

Question 2

• Explanation: In a physical change, the makeup (chemical composition) of matter does not change. Only the physical state or appearance changes.
• Answer: F

Question 3

• Explanation: Evaporation is the process where liquid water turns into water vapor (gas). The substance is still water, just in a different physical state. So it is a physical change and the statement is correct.
• Answer: T

Question 4

• Explanation: As explained in question 3, evaporation is a physical change (change of state of water).
• Answer: T

Question 5

• Explanation: Burning wood involves a reaction with oxygen. New substances like ash, carbon dioxide, etc., are formed. This is a chemical change, not a physical change.
• Answer: F

Question 6

• Explanation: Combining hydrogen and oxygen to make water is a chemical reaction ($2H_2 + O_2

ightarrow2H_2O$). New substance (water) is formed from hydrogen and oxygen. So it is a chemical change, not a physical change.

• Answer: F

Question 7

• Explanation: Breaking up concrete only changes its physical form (size of the pieces). The chemical composition of the concrete does not change. So it is a physical change.
• Answer: T

Question 8

• Explanation: Sand being washed out to sea from the beach is a process of moving sand (a physical transfer). The chemical composition of the sand does not change. So it is a physical change, not a chemical change.
• Answer: F

Question 9

• Explanation: When ice cream melts, it changes from solid to liquid state. The substance is still ice cream (the chemical composition does not change). So it is a physical change, not a chemical change.
• Answer: F

Question 10

• Explanation: Acid rain damaging a marble statue involves a chemical reaction (marble is mainly $CaCO_3$, and acid in rain reacts with $CaCO_3$). New substances are formed, so it is a chemical change, not a physical change.
• Answer: F

The answers for the questions (1 - 10) are: 1. F, 2. F, 3. T, 4. T, 5. F, 6. F, 7. T, 8. F, 9. F, 10. F

Answer:

To solve these true - false questions, we analyze each one based on the definitions of physical and chemical changes. A physical change is a change in the form or appearance of a substance without changing its chemical composition. A chemical change involves a change in the chemical composition of a substance, often accompanied by the formation of new substances.

Question 1

• Explanation: Changing the size and shape of wood only alters its physical appearance. The chemical composition of the wood remains the same. So this is a physical change, not a chemical change.
• Answer: F

Question 2

• Explanation: In a physical change, the makeup (chemical composition) of matter does not change. Only the physical state or appearance changes.
• Answer: F

Question 3

• Explanation: Evaporation is the process where liquid water turns into water vapor (gas). The substance is still water, just in a different physical state. So it is a physical change and the statement is correct.
• Answer: T

Question 4

• Explanation: As explained in question 3, evaporation is a physical change (change of state of water).
• Answer: T

Question 5

• Explanation: Burning wood involves a reaction with oxygen. New substances like ash, carbon dioxide, etc., are formed. This is a chemical change, not a physical change.
• Answer: F

Question 6

• Explanation: Combining hydrogen and oxygen to make water is a chemical reaction ($2H_2 + O_2

ightarrow2H_2O$). New substance (water) is formed from hydrogen and oxygen. So it is a chemical change, not a physical change.

• Answer: F

Question 7

• Explanation: Breaking up concrete only changes its physical form (size of the pieces). The chemical composition of the concrete does not change. So it is a physical change.
• Answer: T

Question 8

• Explanation: Sand being washed out to sea from the beach is a process of moving sand (a physical transfer). The chemical composition of the sand does not change. So it is a physical change, not a chemical change.
• Answer: F

Question 9

• Explanation: When ice cream melts, it changes from solid to liquid state. The substance is still ice cream (the chemical composition does not change). So it is a physical change, not a chemical change.
• Answer: F

Question 10

• Explanation: Acid rain damaging a marble statue involves a chemical reaction (marble is mainly $CaCO_3$, and acid in rain reacts with $CaCO_3$). New substances are formed, so it is a chemical change, not a physical change.
• Answer: F

The answers for the questions (1 - 10) are: 1. F, 2. F, 3. T, 4. T, 5. F, 6. F, 7. T, 8. F, 9. F, 10. F