30 4) quarta 3) calcium teldepar 2 pyroxene 2) many moons size 31 The inner plan

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30 4) quarta 3) calcium teldepar 2 pyroxene 2) many moons size 31 The inner planet 3) cold t oeof ed with 1) an impact on Earth by a 32 The onigin of our moon in a gravity as au The most abundant gas in the Universe is 1) helium 2) oxygen 3) nitrogen 4) hydrogen. 3) carbon dioxide 4) none material let over from the Big Bang 4 34 The most abundant gas on Earth is 1) ntrogen 2) oxygen of these 3s The process by which the planets formed around our Sun is known as: 1) Big Bang Theory 2) condensation of the solar nebula 3) 36 The process by which the Earth separated out into layers during its formation is known as t) sedimentation 2) differentiation 3) Bowen's Reaction Series 4) none of these. is closest to: 1) 4.6 million years 2) 46 million years 3)46 billion years 4) 10 billion to 15 billion years 38 Subduction zones are generally places where the lithospheric plates are: 1) created 37 The age of the Earth based upon radioactive dating 2) separating 3) destroyed 4) all of these 39. The magnetic field that surrounds the Earth flows from: 1) the South Pole to the North Pole 3) from the Equator to the South Pole 4) the lithosphere 2) the North Pole to the South Pole to the asthenosphere 40 The "Supercontinent" from which all subsequent continents were later derived according to Wegener was known as: 1) Pangaea 2) Atlantis 3) Gondwanaland 4) Laurasia 41. Tectonic hot spots are best characterized by which volcano? 1) Mt. St. Helens in Washington 2) Kilauea in Hawai 3) Mt. Fujil in Japan 4) none of these 42 The outer portion of the Earth that is composed of moving solid plates is known as the 1) asthenosphere 2) lithosphere 3) hydrosphere 4) only the continental crust 43. Paleomagnetism is: 1) the magnetic striping pattern in oceanic basaltic rocks 2) evidence for 3) evidence that Earth's magnetic field has flipped many plate tectonics at divergent margins times 4) all of these 44. In 1912, Alfred Wegener's continental drift theory was not accepted by geologists since his hypothesis lacked: 1) fossil evidence 2) similar rock types on distant continents 3) an explanation of a driving mechanism 4) a geology degree

Explanation / Answer

ANSWER:

Calcium is a chemical element with symbol Ca and atomic number 20. An alkaline earth metal, calcium is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium.

The name derives from Latin calx "lime", which was obtained from heating limestone. Its compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. It was isolated by Humphry Davy in 1808 via electrolysis of its oxide, who named the element. While the pure metal does not have many applications due to its high reactivity, it is often used as an alloying component in small quantities in steelmaking, and calcium–lead alloys are sometimes used in automotive batteries. Calcium compounds on the other hand are very widely used in many industries: for example, they are used in foods and pharmaceuticals for calcium supplementation, in the paper industry as bleaches, in cement, in the manufacture of soaps, and as electrical insulators.

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