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.
Heavier elements like iron tend to sink toward the center or core of the earth. Lighter materials, the silicates, oxygen compounds and water have risen to become part of the crust. This action has created distinct layers within the earth and is still in process today. The Inner Earth is composed of three main parts; the crust, the mantle, and the core as shown in the diagram of the earth's interior below: The Crust - silicate rocks, primarily granite and basaltOceanic Crust - mostly basaltContinental Crust - igneous, metamorphic, and sedimentary rocks.