They aren't too easy (the only easier option you're taking really is Lit&Lang instead of pure Lit), it's a good subject combination

Although you should also think about what you might want to do after IB as this can change your subject choices.
The only thing I'm not 100% about is whether your language combination is allowed any more. They no longer have A1 and A2 languages, only 'A' languages. You must take at least 1 A language, but I don't think you're allowed to do 2 (you have listed 2). I think your second language has to be at B or Ab initio level because they want to encourage you to take up a new language or something like that. You should check with your IBC as I'm not sure - or actually maybe somebody who knows will post after me on this thread

The languages system has changed recently.
Chemistry is a difficult subject to do well in. I'd characterise it as challenging

You really need a good teacher to do well in Chemistry because the concepts are difficult to teach and you need to do well in your coursework. If you can get your head round the ideas and put a lot of effort in, you stand a chance of getting a decent mark. It is an intellectual subject though - you can't just get away with putting the hours in and working hard to do well, you do also have to really know what's going on and have a deeper understanding in order to answer some of the exam questions.
Re: Lit versus Lit& Lang, Literature is purely the analytical study of novels. Lit&Lang is a small bit of analysis mixed in with some common sense basics. Common sense basics being stuff like the fact that they use persuasive language in adverts, biased language in newspapers... it's a bit like TOK, actually, and TBH if you can't identify persuasive language in an advert, heaven help you!

Generally I would say you're a very unusual person if you found pure Literature easier than Lit & Lang! Literature is the harder option, however both are now considered to be 'A' languages so technically they're both equal. Unless you want to apply for English or Law or a subject requiring analytical skills (in which case, definitely do Literature) it's really up to you which you do.