Question

felipe wanted to freeze soda to make popsicles. he knew that soda contains carbon dioxide gas, which forms bubbles as it escapes from the liquid. he wondered if the popsicles would freeze more quickly if he removed the carbon dioxide. felipe took the lids off three small bottles of soda. he left the lids off overnight so that carbon dioxide could escape from the bottles. he kept the lids on three other bottles to keep the carbon dioxide in. the next morning, felipe placed all six bottles in the freezer. after two hours, he checked whether soda in any of the bottles had frozen. in this experiment, which were part of a control group? the bottles with lids taken off the bottles with lids kept on soda with carbon dioxide bubbles

Explanation:

Step1: Define control group

A control group in an experiment has normal conditions.

Step2: Identify normal - condition group

The bottles with lids kept on have normal gas - containment conditions while others have lids off for gas to escape. So they are the control group.

Answer:

The bottles with lids kept on