In the Reaction CO+2H²-->CH³OH, 1.27 g of CH³OH are made in the lab. The Percent yield of this reaction is___.

Question

Would the answer be 42?

Pick a number, any number. You need to know how much CO OR H2 you started with. As it stands, the answer is indefinite.

so... it dosent matter what number i answer with?

If the question is as you posted it, no, I don't think any answer will do.
Technically,
%yield=(1.27/theoretical yield)x100 = ??

Since you don't have a number to put into the equation for theoretical yield, I would answer "indeterminate" or "depends upon theoretical yield".

ooooh, i Get it! sounds simple.. Thanks!!