What is the acid_base pair which produce sodium carbonate
Since this is not my area of expertise, I searched Google under the key words "produce sodium carbonate " to get this possible source:
https://en.wikipedia.org/wiki/Sodium_carbonate
Scroll down.
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html