Answer:
The correct option is: d. light isotopes move faster than heavy isotopes and thus are more readily evaporated
Step-by-step explanation:
Evaporation is the process by which water present in liquid state changes into water vapor.
Since, oxygen has two isotopes: ¹⁶O (light isotope) and ¹⁸O (heavy isotope). Therefore, water molecule that consists of ¹⁶O is known as light water (H₂¹⁶O). Whereas, water molecule that consists of ¹⁸O is known as heavy water(H₂¹⁸O).
Since evaporation of heavier water molecules (H₂¹⁸O) is difficult than evaporation of light water molecules (H₂¹⁶O).
Therefore, the water vapor formed by evaporation is rich in light water (H₂¹⁶O).