A chemistry tutor for Sebastião, 17, who's falling behind

My nephew, Sebastião, is 17 and in the final year of school. Sebastião loves school but chemistry has been a struggle since the school was closed during the move. The university entrance exam is in November. We can't afford a private tutor, and the school's free sessions are full. We're looking for a volunteer who could spend an hour or two a week, in person in Duque de Caxias or online, for about twenty weeks. Sebastião is polite, hardworking and eager. We have a quiet space and a laptop for online sessions. I'll always be at home for in-person sessions. If you're a teacher, student or professional who feels comfortable in chemistry, you could change the course of Sebastião's year. Please ask me anything in the questions section. I'll answer honestly and quickly.