Answer
As density of ice is less than density of water i.e. for same mass, ice occupies more volume than water. when milk jug filled with water kept in freezer water freezes and swells to occupy more volume. This swelling ruptures the jug.
Work Step by Step
As density of ice is less than density of water i.e. for same mass, ice occupies more volume than water. when milk jug filled with water kept in freezer water freezes and swells to occupy more volume. This swelling ruptures the jug.