A student investigates some solid samples using thin-layer chromatography (TLC). The student also measures the melting point of each sample. Which results should the student expect from a pure sample?
2 spots, melting point 135 ∘C135\ ^\circ\text{C}135 ∘C
1 spot, melting point 131–135 ∘C131\text{--}135\ ^\circ\text{C}131–135 ∘C
1 spot, melting point 135 ∘C135\ ^\circ\text{C}135 ∘C
3 spots, melting point 131–135 ∘C131\text{--}135\ ^\circ\text{C}131–135 ∘C