In scientific notation. Choose the answer with the proper number of significant figures. (3x10^4) (4x10^23)

A. 12^27

B. 12 x 10^27

C. 10 x 10^27

D. 1 x 10^28

It would be choice B.

This is because the 3 is distributed to the 4 to get 12. The 10^4 is distributed to the 10^23 and because of the exponent laws, the exponents are added to get 27 and the 10's (being the base) is left alone.