Final answer:
Chromosomes are in the form of chromatin during telophase and interphase, where they are less condensed to facilitate transcription and replication.
Step-by-step explanation:
Chromosomes appear as chromatin during the phases of telophase and interphase. This is when the DNA is in a less condensed form, allowing for the necessary transcription and replication processes to take place. During the other phases of mitosis such as prophase, metaphase, and anaphase, the chromosomes are highly condensed and visible under a microscope. In contrast, during telophase, the decondensation process begins, and the nuclear envelope starts to re-form around the chromosomes. Throughout interphase, the genetic material is in the form of a loosely packed chromatin network, ensuring the DNA is accessible for the cell's machinery.