A good thermal conductor is a piece of material that conducts heat fast. This means it accepts heat readily but it also looses heat at the same rate of change.
Yes, that is what "good thermal conductor" means.
No, krypton is not a good thermal conductor. It is a noble gas and has very low thermal conductivity compared to other materials.
steel
No, potassium is not a good thermal conductor compared to other materials. It has a relatively low thermal conductivity, meaning it is not efficient at transferring heat.
Astatine is not a good thermal conductor. It is a poor conductor of heat due to its low thermal conductivity, similar to other halogens. This makes astatine a relatively inefficient material for transferring heat.
Galena is not a good conductor of electricity. However, it is a good conductor of heat due to its high thermal conductivity.
fabric
No.
i forget
Yes, being a metal, aluminum is a good thermal conductor.
Copper is a good electrical and thermal conductor.
a metal