In the reaction above m, what is the ratio of moles of O2 reacted to moles of CO2 produced? show work for brain list

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?