Question

Non-metals are generally a poor conductor of heat and electricity but which one is the poorest of all?

Answer 1

The term bad conductor comes in because there is no perfect or ideal insulator in practice - be it electrical or thermal.
Material which does not allow electrical current to pass through it is termed “electrical insulator “, and same goes for thermal insulator.
These materials possess a very high resistivity to electrical charge flow or thermal conduction. As a general rule, good electrical conductors are also good thermal conductors, and and bad conductors of electricity are bad conductors of heat.
However there are two commonly known exceptions to the rule- mica and acidulated water, which behave differently in thermal and electric conduction properties.graphite is a good conductor

hope it helps you