Context: Hydrogen is commonly used in power stations as a coolant in generators due to a number of favorable properties that are a direct result of its light diatomic molecules. These include low density, low viscosity, and the highest specific heat and thermal conductivity of all gases.

Question: How is hydrogen used at power stations?
Answer: as a coolant in generators

Question: Why is it used as a coolant?
Answer: favorable properties that are a direct result of its light diatomic molecules

Question: What are these properties?
Answer: low density, low viscosity, and the highest specific heat and thermal conductivity of all gases