Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Minerals form from dissolved substances when water evaporates. Answer: evaporation
[EX A]: What process does water undergo to leave behind dissolved substances?

[EX Q]: Passage: The strong nuclear force works only over very short distances. As a result, it isn't effective if the nucleus gets too big. As more protons are added to the nucleus, the electromagnetic force of repulsion between them gets stronger, while the strong nuclear force of attraction between them gets weaker. This puts an upper limit on the number of protons an atom can have and remain stable. If atoms have more than 83 protons, the electromagnetic repulsion between them is greater than the strong nuclear force of attraction between them. This makes the nucleus unstable, or radioactive, so it breaks down. The following video discusses the strong nuclear force and its role in the atom. The video also introduces the weak nuclear force, which is described next. Answer: unstable, or radioactive
[EX A]: If the electromagnetic repulsion between protons is greater than the strong nuclear force of attraction between them, what do they become?

[EX Q]: Passage: A sex-linked trait is a trait whose allele is found on a sex chromosome. The human X chromosome is significantly larger than the Y chromosome; there are many more genes located on the X chromosome than there are on the Y chromosome. As a result there are many more X-linked traits than there are Y-linked traits. Most sex-linked traits are recessive. Because males carry only one X chromosome, if they inherit a recessive sex-linked gene they will show a sex-linked condition; there is no dominant allele to offset the recessive allele. Answer: sex-linked trait
[EX A]:
What is a trait whose allele is found on a sex chromosome called?