Question

what is the precaution to be taken while doing the activity to know the reaction of oxygen with metals and non metals

Answer 1

When oxygen reacts with other elements, metals and non-metals, many times the reaction involves the production of heat. Oxygen reacts with magnesium in what is termed as a combustion reaction, producing heat to the tune of 2200°C. These amount of heat is too high and any one carrying out such experiments needs to be extra careful. When oxygen reacts with most metals, while burning, sparks are most likely to be generated. This can also cause harm to those participating in the experiment if not controlled.
With some non-metals, like hydrogen, oxygen reacts explosively. This is also quite a dangerous experiment if not controlled.
In general terms, experiments involving oxygen, especially combustion, risk of getting injured is quite high, hence precautions should be taken.