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.
b/c the densest make up the core the layers from because heavier elements are pulled toward the center of the earth by gravity list the 3 layers of the Earth, based on their chemical composition crust