Why can your nose tell coffee apart from oranges?

Answer: Their odor molecules activate different combinations of sensors in the nose

Their odor molecules activate different combinations of sensors in the nose ✓ — Different odor molecules stimulate different combinations of smell receptors, proteins on sensory cells in the nose. The brain interprets the pattern of signals as a particular smell. One receptor type can respond to several molecules, so there is not a separate receptor for every odor.

The nose sorts odor molecules only by how much they weigh — The nose does not identify an odor by weighing its molecules. Molecular chemistry determines which smell receptors respond, and the brain reads their combined activity. Similar molecular weights need not mean similar smells.

The nose identifies each object from the temperature of its vapor — Vapor temperature is not an identity label for a smell. Warming can change how much of an odor reaches the nose, but coffee and oranges remain distinguishable because their molecules activate different receptor patterns.