[xbrittty]

Hello!
I was wondering whether, as I cannot find an answer on google, that will the decomposition of Sodium Thiosulfate have any affect towards the molar concentration of the Sodium Thiosulfate solution?
And also, what will potassium iodide solution oxidize to if it was to be oxidized by O2 in air.
This is much appreciated, thank you! 

[xbrittty]

Have any effect*

[Borek]

So basically you are asking if after substance decomposed it is still present in the solution?

[xbrittty]

Yes   
And will it have any effect to the molar concentration. For example, will it decrease the molar concentration?
If that makes any sense...
Thank you for replying to my question!

[Borek]

My question was intended as a HUGE hint.

Say you have a $10 bill. You put it into a shredder. After that do you still have $10?

Say you have a solution of thiosulfate. Thiosulfate decomposes...

[xbrittty]

Oh my goodness, I feel so stupid now.
Thank you very much!
I appreciate your help, and once again, thank you for replying back! 

[Arkcon]

I'm not adding a perfect analogy to Borek:'s initial one, but consider the $10 bill in the shredder.  If you shred 3/4 of it, you don't have any money left.  If you shred 1/4 of it, you do, people look at it funny, but still accept it.  If you shred 49% or 51%, you may, or you may not, depending on the person who might accept it.  If you're going to perform a titration, you will have to account for decomposition of the solution, it all depends on how much is gone over what period of time, how accurate you need it be, how recently you've checked, etc.

[opsomath]

To answer your other question, you get iodine (I2) if I- gets oxidized by oxygen.