Will my students see this exercise and formative assessment, as yet another test or exam?

It should be part of an engaging lesson and class activity and not presented as a test. A variety of formative assessment activities for many areas of chemistry can be found on the RSC's Assessment for Learning website, eg it could take the form of asking students to draw a concept map. This allows you, their teacher, to gain valuable insights, as a type of pre-test, checking their understanding.

Would I need to use the whole activity or is it suitable to use a section of this activity?

You can use the whole or part of the activity as appropriate to your students. For example, the summary page with the four diagramatic representations of the combinations of weak, strong, concentrated, dilute could be used to makes clear contrast and comparisons, to draw out the differences or to check understanding.