Given a scientific passage and an answer, generate a question for the given answer.
One example is below.
Q: Passage: A frameshift mutation is a deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in RNA:. Answer: nucleotides.
A: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Rationale: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.
Q: Passage: Strontium is a silver-colored alkaline Earth metal that is even softer than calcium. Strontium compounds are quite common and have a variety of usesfrom fireworks to cement to toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, like the one pictured in the Figure below , the compound strontium chloride reduces tooth sensitivity. Answer: strontium
A:
What is a silver-colored alkaline earth metal that is even softer than calcium?