How the AP Chemistry composite works
Your raw results in each section are converted to a percentage of the points available, then averaged because multiple choice and free response are each worth 50%. The 60 multiple choice questions and the 46 free response points are weighted equally, and the combined composite percentage maps to a predicted 1-5 score using common estimated thresholds.
Using the estimate wisely
Chemistry curves change with exam difficulty, so a borderline composite can round either way. The long free response questions carry the most points, so partial credit there often moves your score more than a few extra multiple choice answers.