What is the name of a functional group that is attached to this hydro carbon? need

Chemistry worksheet - i am not sure what they are asking for exactly?

Which scenario is most similar to the type of collision that gas particles have according to kinetic molecular theory

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?