Please don’t do this:

 you: Hi
 me: Hello.

  ... time passes ...

 you: I'm working on [something] and I'm trying to do [etc...]
 me: Oh, that's [answer...]

This is like calling someone on the phone and then putting them on hold.

Instead, try this:

 you: Hi -- I'm working on [something] and I'm trying to do [etc...]
 me: [answers question]

This is way more likly to get you an answer sooner, and it avoids making the other person wait. Instead, they can start thinking about your question immediately.

I know folks are trying to be polite by not jumping right into a question or request, like they would do in-person or on the phone, but chatting online is neither of those things.

The same applies to “Hi, are you there?” or “Do you have a minute?” or “ping”. Assume I’ll get your chat message at some point and just ask your question.

If you feel uncomfortable just asking the question, you can do something like this instead:

2020-07-10 12:32:12 you: Hi! If you're not busy I was wondering if I could ask a question.  I'm working on [something] and I'm trying to do [etc...]

Asking your question before getting an initial reply allows for asynchronous communication. The other person can still answer your question and you’ll get the answer when you return.