I HATE CHEMISTRY RIGHT NOW

so i was away last week for three days due to my toe got so infected it hurt to walk on (TMI i know) and i had chemistry today and i had to sit in a empty room to do MY MILESTONE and i need to pass it to carry on but IM SCARED I FAILED BECAUSE I KEEP MIXING UP THE EQUATIONS AND I DONT KNOW IF I USE HYDROGEN OR H2O TO BALANCE OXYGEN! pray for me that i passes guy PLEAASEE 😭🙏