Yes! There is! It’s the Web Applications Stack Exchange site. As explained in the help center for that site:
What topics can I ask about here?
Web Applications Stack Exchange is for expert and advanced users of web applications.
If your question generally covers …
Using Gmail, Facebook, Twitter, Google, or any other website which behaves ...
There's no site in the network dedicated to calendars and related topics. But I don't think you need to worry:
History Stack Exchange has quite a few question about historic calendars (74 while I'm writing this).
Astronomy doesn't have a dedicated calendar tag but it does have some questions about modern calendars.
Several religious sites in the network ...
I do it only if I see some indications that the author of the post has a hunch about the nature of Meta Stack Exchange.
In this case, they tagged their question site-recommendation and indicated they weren't sure about the correct Stack Exchange site. Especially the former is an indication that this is more than just a run-of-the-mill 'lost soul'. I know ...
Drone are on-topic on Aviation Stack Exchange, where they're called unmanned aerial vehicles. However, your question looks like a shopping recommendation which are off-topic on almost all Stack Exchange sites. Almost; we make an exception for software and hardware, and it turns out the latter site welcomes questions about drones.
No, it does not.
There is (or, at least, was) a process for new Stack Exchange sites to be created, using a site called Area 51.
One of the main people in charge of Area 51 was fired earlier this week, so whether things will change moving forward hasn't yet been clarified, but in general, it is safe to say that there is not a SE site for every topic.
The help center posts "What topics can I ask about here" should help you judge whether a question is on topic for a given SE site. Look at those rather than looking at the available tags.
Your question could be on topic for Biology.SE if it is written to focus on biological concepts or drug mechanisms
Your question is about greenhouse gases, so I think Earth Science is the right site. They have quite a few questions about greenhouse gases. The fact that you encountered this question in a test isn't particularly relevant in determining the correct site; it's what we call meta information.
Note that for a good question, you'd probably need to include the ...
SoundCloud qualifies as a web application and (without seeing your actual question) Web Applications Stack Exchange might be a good fit. Please use the search function (your question might have been asked already) and if not, check their help center before asking your question.
SoundCloud has mobile apps, so if your question is specific to one of those apps,...
Psychology & Neuroscience or Medical Sciences might be good candidates to ask questions about that topic.
Be sure to read the policies manifested in these sites' help-centers, to ask an on-topic question though.
I am not so sure that there's really an appropriate, unambiguous site you can ask such broad question.
You are constructing a hypothetical situation, which could well fit as a question at SE Worldbuilding.
On the other hand you're asking about certain SI units, which tends more to be answered at SE Physics.
However I have no idea how one would go ...
The Biology.SE site returns the most hits for the search term "Optogenetics".
"How does optogenetics work?"
More importantly, you can see that the moderator uses the technique in his lab.
"How long does Lentivirus take to express in vivo mouse neurons?"
Only based on the title:
Proper SE Site to ask about freelancing consideration (like best price suggestion, freelancer sites)
No site within the SE network is suitable for that question. What you're asking is a recommendation question, looking for an off-site resource or more popular expressed: a shopping question. Those type of question are not a good ...
At the moment your question is a bit vague (but maybe that was intentional). If you can supply more details (photos etc.) it might be welcomed by Engineering Stack Exchange. They have quite a few questions about automotive engineering and I suspect your question might fit under that umbrella. For example, this question about military vehicle design: What is ...