स्वेच्छा से तेजाब फेंकना या फेंकने का प्रयास करना भारतीय दंड संहिता की किस धारा के तहत अपराध है?

Hiring or conniving at hiring persons to join an unlawful assembly is an offence punishable under which Section of the Indian Penal Code?

'X' threatens 'Y' that he will post defamatory statements on social media unless 'Y' pays him money. Which offence under the Indian Penal Code has 'X' committed?