Zadanie 1c
Wzorowane na: Chemistry HL Paper 3, November 2023, TZ2, pytanie 1(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 1a-1d.
Grapefruit juice is a rich source of vitamin C (ascorbic acid). To destroy pathogenic bacteria, producers often heat-treat the juice by filling it into bottles at 85 °C. A food laboratory monitored the concentration of vitamin C in heat-treated juice and in untreated, cold-pressed juice. Both were stored in partly filled clear glass bottles at 10 °C for 56 days.
Polecenie
The concentration of vitamin C and the pH of juice from five different fruits were measured.
| Fruit | Concentration of vitamin C / mg dm−3 | pH |
|---|---|---|
| Melon | 33 | 6.20 |
| Papaya | 56 | 5.60 |
| Plum | 81 | 4.05 |
| Kiwi | 154 | 3.45 |
| Guava | 205 | 4.55 |
Deduce, with a reason, whether the data show a correlation between the concentration of vitamin C and pH.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
yes AND the calculated correlation coefficient is −0.66 «a moderate negative correlation»
OR
yes AND guava is an outlier «the other four fruits show lower pH at higher concentration»
OR
no AND guava has the highest concentration of vitamin C but an intermediate pH ✔
Schemat punktowania
Award [1] for a clear yes or no supported by a reason taken from the data, calculated or described in words. A bare statement of the type or strength of the correlation earns nothing. A claim that r = −0.66 means the correlation is weak is rejected.
Komentarz
Without guava the correlation coefficient would be −0.92; one point is enough to weaken the apparent trend.