Out of the options, the best indicator is a color change since it is the only one that can't really be blamed on a physical change. you will eventually notice that during qualitative labs and some quantitative labs, usually the thing that you are looking for is either color change or the production of a precipitate to indicate the presence of a chemical reaction
A chemical change occurs when a new substance is formed or the original substance changes its identity and composition due to a chemical reaction. This is the opposite of a physical change that modifies only physical properties such as state or shape. Moreover, a chemical reaction can be identified because if often leads to a change in color, odor, the formation of bubbles or temperature change. This implies the only one that suggests a chemical change is a change of color because this occurs if the composition of a substance or substances change.
<span><span>The reaction is as follows: C6H6 </span>+ HNO3 + H2SO4 ------------> </span>C6H5NO2<span> + H</span>2<span>O (BENZENE) (NITRIC ACID)(CATALYST) </span>NO2(+) is the electrophile that acctacks on the benzene ring in nitration process.
