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.
Structure of the Earth. The Earth is made up of many rocky layers. The solid, outer layer is called the crust. Below the crust lies a layer of very hot, almost solid rock called the mantle. Beneath the mantle lies the core. The outer core is a liquid mix of iron and nickel, but the inner core is solid metal. Sometimes, hot molten rock, called magma, bursts through Earthâs surface in the form of a volcano.