Must a pregnant woman who suffers from constant gas and sounds emanating from her, and performs ablution for each prayer, pray standing, or is it permissible for her to pray sitting on a chair, especially given the pain in her hands that prevents her from performing a full prostration?

If the sounds in the abdomen are merely gurgling unaccompanied by the expulsion of gas, then they do not invalidate ablution. However, if you suffer from incontinent flatulence, you must perform ablution for each prayer after its time has begun, and you may pray the obligatory and supererogatory prayers with that ablution, which becomes invalid upon the expiry of the prayer's time. If your gas causes distress to other worshippers, it is advisable to pray at home. You must pray standing if you are able; otherwise, sitting, then lying on your side. If you are unable to prostrate or if it is difficult for you, then gesturing is permissible.