Question

It is said that metals are the good conductor of heat so how in metal bottles water is kept cold for a long duration

Answer 1

The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask (metal bottle you referd ) by conduction.

flask is an isolated system which do not allows transfer of heat .

you will study about different kind of thermodynamic system later .