Which of the following terms are unitless?

Options

A. Molality
B. Molarity
C. Mole fraction
D. Mass per cent

Explanation

To determine which of the given terms are unitless, we will analyze each term one by one: molality, molarity, mole fraction, and mass percent.

### Step-by-Step Solution:

1. **Molality**:
- Definition: Molality is defined as the number of moles of solute per kilogram of solvent.
- Formula:
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