Final answer:
Phosphorus can leave yellowish-white stains, while iodine leaves purple stains or brownish stains when in solution. The closest match to the options provided for the color of stains left by phosphorus and iodine is red/yellow, even though the true colors are slightly different. Therefore correct option is B
Step-by-step explanation:
Phosphorus and iodine can leave characteristic stains when they come into contact with surfaces. Elemental phosphorus is not commonly found because it reacts rapidly with oxygen; however, white phosphorus can leave yellowish-white stains. Iodine, as a solid or when sublimed, can leave purple stains due to its characteristic color. This is seen when iodine vapor comes into contact with a cool surface, where it deposits as solid iodine, which is dark purple. On the other hand, a solution containing iodine, known as Lugol's iodine, can leave a brownish stain. From the options provided, if we consider just the pure elements, neither option perfectly fits, but the closest match to the phosphorus and iodine stains described here is option B. red/yellow, which corresponds to red for iodine (closest to purple) and yellow for phosphorus.
Looking at the information provided, we can also see a reference to phenolphthalein, an indicator that turns pink in basic conditions, and the fact that substances are blue on red litmus paper if they have a pH higher than 7. While interesting, these details do not alter the answer regarding the stains left by phosphorus and iodine.
Thus, based on the information given about the colors associated with these elements, we can infer the stains left by phosphorus and iodine would most closely resemble red and yellow stains respectively. However, as mentioned, iodine does not typically leave a red stain, so this correspondence is an approximation based on the given options.