Which is a better conductor of thermal energy a plastic foam cup or window glass?

Window glass is a much better conductor of thermal energy than a plastic foam (styrofoam) cup. The exact "thermal conductivity" rating of window glass depends on its mineral composition . The thermal conductivity of styrofoam is very low, because it traps air in small pockets, and air has a very low thermal conductivity. That is why styrofoam is widely used as insulation.

Mfjh f fb gcbb etyb yryh htbgh g yrjjj t n   j tj