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.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures