TASK DEFINITION: Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
PROBLEM: molar mass is the mass of a substance that has 6.022 × 10 atoms (avogadro's number).

SOLUTION: molar mass

PROBLEM: a dipole speaker is a type of a loudspeaker.

SOLUTION: dipole speaker

PROBLEM: sun angle is the angle of incidence at which sunlight strikes the earth at a particular time and place.

SOLUTION:
sun angle