Question

explain isolated system

Answer 1

Its a term which is mostly used in chemistry especially in thermodynamics
well first of all let me explain what is a system well a system is a defined specific part of universe or specified portion of the matter which is under experimental investigation and the rest of universe I.E other matter except the system is know as surrounding
well isolated system is a type of system which has no interaction with its surroundings. The boundary *(between system and surrounding)is sealed and insulated . Neither matter nor energy can be exhanged with the surrounding . 
for example: a substance in an ideal thermos flask
Hope this helped you
:-)