Using the equation below, which of the following provides evidence that a chemical reaction took place?

Question

2NO (colorless gas) + O2 (colorless gas) --> 2NO2 (brown gas)

Using the equation below, which of the following provides evidence that a chemical reaction took place?



2NO (colorless gas) + O2 (colorless gas) --> 2NO2 (brown gas)

The total number of atoms on the products and reactants side of the equation are the same

A precipitate formed

A color change occurred

A gas is produced

Answer 1

The evidence that a chemical reaction took place in this case is that a color change occurred. Initially, the reactants are colorless gases (NO and O2), but the product is a brown gas (NO2). Colors can indicate the formation of new substances and the occurrence of a chemical reaction.