Answer:
One low density 14N/14N band up, and one intermediate heavier 15N (template)/14N( for synthesis) of higher density band below.
This is because in the first generation the light 14N and heavy 15N were distributed in equal proportion in the bacterial so that each strand of the double DNA consists of half heavy 15N template and half light 14N. Therefore all the strands are intermediate in composition.
According,to semi conservative replication, after second generation one half of the lighter N14 strands will serve as the template, while the other half N14 strands will be used for s DNA synthesis. While one half of 15N strand will serve as the template , and one lighter 14N will serve new synthesis of DNA to formed intermediate band,
