Gases make better thermal insulators and is due to the more inter molecular distance, and the weak forces among particles of gases.
Step-by-step explanation:
The speed of heat transfer by conduction is varies for different materials. If the materials is less dense they are better insulators and if the material is more dense its insulating property is very less.
An insulator is a material that is poor conductor of heat. In gases the inter molecular forces of attraction is weakest. The particles are very apart from each other.