Which of the following features is associated with a self-sustaining nuclear chain reaction?

1. Products are of comparable mass to fission nuclei.
2. The average number of neutrons released per nuclear that bombard other nuclei is more than one.

Nuclear fission is the process of splitting a nucleus into roughly equal parts, and releasing energy and neutrons in the process. If these neutrons are captured by another unstable nucleus, they can do fission as well leading to a chain reaction. The average number of neutrons released per nucleus that go on to fission another nucleus is referred to as k. Values of k larger than 1 mean that the fission reaction is releasing more neutrons than it absorbs. Therefore, it is referred to as a self-sustaining chain reaction.