Which of the following is not true about differences between novae and supernovae?

The claim that supernovae eject gas into space but novae do not is not accurate. In reality, both novae and supernovae can result in the expulsion of material into space; however, the scale and processes involved are different. In a nova event, a white dwarf star accretes material from a companion star, leading to nuclear fusion on its surface, which creates a temporary but significant increase in brightness. The material is ejected back into space, typically in a less dramatic manner compared to the supernova explosion.

Supernovae, on the other hand, are enormous explosions that occur at the end of a massive star's life cycle or from the runaway fusion in a white dwarf, releasing immense energy and ejecting the outer layers of the star into space. Thus, it is not accurate to say that novae do not eject gas into space; they do, but to a much lesser extent than supernovae. Understanding this distinction highlights the significant difference in the processes and the scale of their respective explosions.