In this experiment, it is important that the benzaldehyde used should be pure. Benzaldehyde is easily oxidized by air and produces a white crystalline material. What is the name of this oxidation product?

Benzoic acid

Explanation:Benzaldehyde is the commonest aldehyde because of its industrial use and it undergoes autoxidation with air to give benzoic acid.1 molecule from aldehyde is reduced to benzyl alcohol and another molecule is at the same time oxidized to benzoic acid.

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but