Final answer:
In the G2 phase, a cell initially with 6 chromosomes will have 12 chromatids and 24 strands of DNA.
Step-by-step explanation:
If a cell has 6 chromosomes during the G1 phase, then after DNA replication in the S phase, and during the G2 phase, it will have 12 chromatids. In G2, each of the original 6 chromosomes will have been replicated into a pair of sister chromatids, making a total of twelve. As for the strands of DNA, since each chromatid is composed of a double-stranded DNA molecule, the cell will have 24 strands of DNA (12 chromatids each with 2 strands of DNA).