Nicotine dependence is now recognized as a psychoactive substance dependence disorder (DSM-IV, ICD-10). Under the DSM-IV criteria smokers are classified as dependent if they exhibit impaired control and continue to smoke despite awareness that it exacerbates a medical condition, and if they experience withdrawal symptoms when abstaining from smoking, or if they have a history of unsuccessful attempts at quitting.
The Earth's outer core is most likely made up of an iron-nickel alloy while the inner core mostly iron and a bit of nickel and cobalt. This is due to inferences that iron, cob â¦ alt and nickel are denser than other materials found at different levels in the structure of Earth, such as magnesium in the mantle.
Earth's core is the deepest, hottest layer, and it's made up of two layers itself: the outer core which borders the mantle and the inner core, which is a ball-shaped layer made almost entirely of metal.