Maintain hygiene in that area. Use mouthwash thrice daily for 1 week. If there is no pain, swelling or pus it will heal eventually. If any symptoms then visit dentist at the earliest. About 2nd molar.. Those are just stains. Nothing to worry. Do professional teeth cleaning (ultrasonic scaling)

Hi sir After the extraction the socket and the tissue goes through the process of healing and regeneration and might turn different colors. This is yellow scab formation, which is absolutely normal. If however you feel a lot of pain and pus coming out of the socket, visit the dentist. The yellowish spot on left lower 2 molar is caries, and it needs filling.