Question

question 6. which are physical and which are chemical changes? a) boil b) burn (combustion) c) condense d) corrode e) melt f) rust g) crush h) freeze i) oxidize j) rot k) photosynthesis

Explanation:

Step1: Recall physical - change concept

Physical changes are changes in state or form without new substances formed.

Step2: Recall chemical - change concept

Chemical changes result in new substances with different chemical properties.

Step3: Analyze boiling

Boiling is a phase - change from liquid to gas of the same substance. It's a physical change.

Step4: Analyze burning

Burning (combustion) involves a substance reacting with oxygen to form new substances like carbon - dioxide and water. It's a chemical change.

Step5: Analyze condensing

Condensing is a phase - change from gas to liquid of the same substance. It's a physical change.

Step6: Analyze corroding

Corroding is a chemical reaction where a metal reacts with substances in the environment to form new compounds. It's a chemical change.

Step7: Analyze melting

Melting is a phase - change from solid to liquid of the same substance. It's a physical change.

Step8: Analyze rusting

Rusting is the oxidation of iron in the presence of oxygen and water to form iron oxide. It's a chemical change.

Step9: Analyze crushing

Crushing changes the physical form of a substance without changing its chemical composition. It's a physical change.

Step10: Analyze freezing

Freezing is a phase - change from liquid to solid of the same substance. It's a physical change.

Step11: Analyze oxidizing

Oxidizing involves a substance reacting with oxygen to form new substances. It's a chemical change.

Step12: Analyze rotting

Rotting is a decomposition process by microorganisms, forming new substances. It's a chemical change.

Step13: Analyze photosynthesis

Photosynthesis is a chemical process where plants use carbon - dioxide and water to produce glucose and oxygen. It's a chemical change.

Answer:

a) Physical change
b) Chemical change
c) Physical change
d) Chemical change
e) Physical change
f) Chemical change
g) Physical change
h) Physical change
i) Chemical change
j) Chemical change
k) Chemical change