Which is an example of making a qualitative observation? 1measuring the speed of the chemical reaction2describing how copper changes color in chlorine3recording how long it takes to burn magnesium4showing the results of an experiment with a graph

There are two options for describing observations. They are either qualitative or quantitative. Since 1, 3, and 4 are all identifying results by qualifying them, process of elimination allows us to choose 2 as the only one left. And describing how copper changes color is obviously not a quantitative observation as they are not reporting any numbers along with the observation.

The answer is 2

2 for sure! because it is describing

The se-ci  bonds is more polar  than s-br bond