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

Passage: It was known that DNA is composed of nucleotides , each of which contains a nitrogen-containing base, a five-carbon sugar (deoxyribose), and a phosphate group. In these nucleotides, there is one of the four possible bases: adenine (A), guanine (G), cytosine (C), or thymine (T) ( Figure below ). Adenine and guanine are purine bases, and cytosine and thymine are pyrimidine bases. Answer: nitrogen
What does the base of a nucleotide within dna consist of?

Passage: Did you ever have a picnic ruined by a surprise rainstorm? People often complain when the weather forecast is wrong. But in fact, weather forecasts today are much more accurate than they were just 20 years ago. Scientists who study and forecast the weather are called meteorologists . How do they predict the weather?. Answer: meteorologists
What do we call scientists who study and forecast the weather?

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
If the electromagnetic repulsion between protons is greater than the strong nuclear force of attraction between them, what do they become?