Zadanie 25
Wzorowane na: Chemistry SL Paper 1, May 2023, TZ1, pytanie 25. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
Which statement best explains why the boiling points of the straight-chain alkanes rise from methane to pentane?
A. The carbon–hydrogen bonds become stronger
B. Longer molecules have more electrons, so the London (dispersion) forces between them are stronger
C. Hydrogen bonds form between the molecules
D. The molecules become more polar
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
B ✔
«successive members differ by a CH2 unit, so molar mass and the number of electrons increase; the London (dispersion) forces become stronger and more energy is needed to separate the molecules. Alkanes are non-polar and cannot form hydrogen bonds, and the strength of the covalent bonds inside the molecules does not decide the boiling point»
Schemat punktowania
One mark for the correct option.