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Stage 1
Answer 4 questions correctly in a row.
Select the chemical formula for this molecule.

P
H
P
H
4
P
H
P
H
3
P
2
H
2
ref_doc_title.
Jumping to stage 1 of 1
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Now entering the Challenge Zone—are you ready?
Answer 4 questions correctly in a row.

Now entering the Challenge Zone—are you ready?