The compound menthol has the structure shown. Some of the carbon atoms are labelled P, Q, R and S.

What is the number of chiral centres in a molecule of menthol?
1
2
3
4
Which of the carbon atoms is responsible for a peak at 72 ppm in the 13C NMR spectrum of menthol?
P
Q
R
S
Four groups of students warmed samples of menthol with sodium dichromate(VI) in acid. They purified the reaction mixture and carried out a series of qualitative tests on the organic product.
The findings of each group in the class are shown in the table.

| Qualitative test | ||
Group | Add 2,4-dinitrophenylhydrazine | Warm with Fehling’s solution | Add PCl5 |
One | ✔ | ✖ | ✔ |
Two | ✔ | ✖ | ✖ |
Three | ✔ | ✔ | ✖ |
Four | ✖ | ✖ | ✔ |
A tick (✔) shows a positive result, a cross (✖) shows a negative result.
Which group recorded the results you would expect?
One
Two
Three
Four
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