The slight error has been to use the prefix mono to name monocarbon.The compound she is most likely naming is:

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As you see, the chemical formula has 1 atom of C, which is likely why she named it mono, and 4 atoms of Br.
The right name is carbon monobromide, i.e. you have to supress the prefix mono, as per IUPAC rules.
The best answer to report is 2.900 g/ml (answer A)
explanation
The best answer to report must be in four significant figures. 2.900 g/ml is therefore the best answer to report since in is in four significant. zeros placed after other digits but behind a decimal point are significant figures.,theerfore 2.900 has four significant figures
The solution with the lowest pH would mean that it is an acid, specifically a strong acid which completely dissociates into ions in aqueous solution. Among the choices listed above, I think the correct answer is option D. It is nitric acid that will have the lowest pH because it is the only strong acid in the group.
Answer:
Is there a picture To go with this?
Explanation: