Final answer:
The size of the transcription bubble is 10-12 nucleotides and the RNA/DNA hybrid within it is 5-6 nucleotides long.
Step-by-step explanation:
The size of the transcription bubble, which is the region of DNA that is unwound during transcription, is around 10-12 nucleotides. This allows the RNA polymerase to access the DNA template strand and synthesize RNA.
The RNA/DNA hybrid in the transcription bubble is approximately 5-6 nucleotides long. This hybrid consists of RNA nucleotides that are paired with the complementary DNA strand.