Question

Decide whether the change is physical or chemical, and try to explain your reasons.
>Some very cold liquid nitrogen is cooled even further, until it freezes
>Some magnesium is heated in oxygen until it burns
>Some sodium chloride is added to a beaker of water, and left to dissolve

Answer 1

Answer:

the whether will be ghenged whith the physical at lass in two hours

Answer 2

Answer:

1. Physical change

2. Chemical change

3. Chemical change

Explanation:

1. Physical change is taking place here as this process is reversible and physical change takes place when the process is reversible. Freezed liqiud nitrogen can be turned back into liquid nitrogen.

2. Chemical change takes place here as irrevesible change takes place here, and when irreversible change takes place, there is a chemical change. Burnt magnasium cannot be converted back into magnesium.

3. Chemical change takes place here as the change is irreversible, and when irrversible change takes place there is a chemical change. The dissolved sodium chloride cannot be get back.