Question

using the molecule below, select the correct statement.
the molecule will yield a positive ninhydrin test turing from a colorless solution to a dark blue - violet.
the molecule will turn biuret reagent from pink or purple to pale - blue.
the molecule will cause the ninhydrin test to change from colorless to yellow.
the molecule will turn biuret reagent from a colorless solution to pink or purple.

Explanation:

1. Analyze the molecule: The molecule has a free amino group ($\ce{H3N+}$) and peptide bonds (–CONH–), indicating it's a peptide/protein - like structure with a free amino terminus.
2. Ninhydrin test: Ninhydrin reacts with free $\alpha$-amino groups (or other free amino groups in some cases) in amino acids, peptides, or proteins. A positive ninhydrin test gives a dark blue - violet color (also called Ruhemann's purple) when reacting with amino - containing compounds.
3. Analyze biuret test: The biuret test is for peptide bonds (presence of at least two peptide bonds). The biuret reagent (containing $\ce{Cu^2+}$ in alkaline conditions) turns from blue to pink/purple (or violet) in the presence of peptide bonds. But the options about biuret have incorrect color change directions (the reagent is blue initially, and the molecule would cause the reagent to change, but the options describe the reagent changing from pink/purple to pale - blue which is wrong, or the molecule turning the reagent from colorless which is also wrong as biuret reagent is blue).
4. Analyze ninhydrin test options: The first option about ninhydrin says it will yield a positive ninhydrin test (dark blue - violet color change from colorless ninhydrin solution), which is correct. The second option about ninhydrin causing a color change to yellow is wrong (ninhydrin gives blue - violet for amino groups, yellow for imino acids like proline but this molecule has a free amino group). The biuret - related options have incorrect color change descriptions.

Answer:

The molecule will yield a positive ninhydrin test turning from a colorless solution to a dark blue - violet. (The corresponding option: "The molecule will yield a positive ninhydrin test turing from a colorless solution to a dark blue - violet." (Note: There is a typo "turing" should be "turning" in the option, but this is the correct option based on content))