Oxygen is obtained through various methods. Which of the following methods involves a chemical change?
1. Electrolysis of water
2. Distillation of liquid air
3. Heating of KCIO,
02
1 and 2
1 and 3

1

Explanation:

Electrolysis is the passing of an current through a conducting solution, when the occurs, a chemical reaction takes place.

Heating a chemical will always cause a chemical reaction, which is why 3 is also correct

Some information as to why 2 is NOT correct.

2 is NOT a chemical reaction, but rather a process of physical separation. It uses selective boiling and condensation, but is not considered a chemical reaction.

as with 3, heating is not considered a chemical reaction, but rather a physical temperature change. This is always what it is considered to be (e.g boiling water is a physical temperature change, not a chemical reaction)

Hope this helps.

Hope this helps.

hi there!

your question asks at which segment does freezing occur.

since we're talking about water, the freezing point of water will be 32 degrees fahrenheit or below.

hope this ! ~