firm support that bears weight of microscope = base
D
This feature is formed at destructive boundaries where the denser plate (usually the oceanic plate) is subducted underneath the less dense plate (usually the continental plate).
Explanation:
the stress in the boundary between the two plates causes them to warp at the boundary forming a trench. This forced bending and the friction between the two plates (remember tectonic plates are very rugged) causes fissures to develop at the boundary. As the denser plate dives into the mantle, it begins to melt and the molten rock rises through the fissures. The magma erupts at the surface in several fissures forming volcanic mountains ranges along the convergent boundary.
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<span>These are five questions with its five answers.
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</span><span>First, we have to explain main question.
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</span><span>The statement provides the chemical equation for the reaction of Fe with water to produce iron(III) oxide and hydrogen.
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</span><span>Fe3O4 is a weird chemical formula. It belongs to the product named oxoiron.
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Next, I have to tell how you must interpret the question. The five questions are based on the complete reaction of the same number of moles as the coefficients indicated in the chemical equation.
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<span>Those coefficients are 3 for Fe, 4 for H₂O, 1 for Fe₃O₄ and 4 for H₂.
With that understood, let's work every question.
1) How many molecules of H₂ are produced?
Answer: 4 moles of molecules.
</span><span>Justification:
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<span /><span /><span>This is, the number of moles of H₂ produced is given by the coefficient indicated in the chemical equation.
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<span>2) How many oxygen atoms are required?
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<span>Answer: 4.
</span><span>This is, the atoms of oxygen are supplied in the molecules of water. Since the coeffcient of water is 4, and each molecule o fwater has 1 atom of oxygen, 4 moles of water contain 4 moles of atoms of oxygen.
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3) How many moles of Fe₃O₄ are formed?
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<span>Answer: 1.
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<span>Justification: the coefficient of for formula Fe₃O₄ is 1, indicating that the theoretical yield is 1 mol of molecules.
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<span>4) What is the mole ratio of Fe to H₂O?
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<span>Answer: 3:4
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<span>Justification:
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</span><span>The ratio is the quotient of the two coefficients: the coefficient of the Fe divided by the coefficient of the H₂O.
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5) How many hydrogen atoms are involved in this reaction?
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<span>Answer: 8 moles of hydrogen atoms.
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<span>Justification: as you can see each molecule of H₂O has 2 atoms of hydrogen, then 4 moles of molecules of H₂O have 8 moles of atoms of hydrogen. And of course the same number are in the produt: 4 moles of H₂ contain 8 moles of atomos of hydrogen
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Answer:
The process of dissolving can be endothermic (temperature goes down) or exothermic (temperature goes up).
When water dissolves a substance, the water molecules attract and “bond” to the particles (molecules or ions) of the substance causing the particles to separate from each other.
The “bond” that a water molecule makes is not a covalent or ionic bond. It is a strong attraction caused by water’s polarity.
It takes energy to break the bonds between the molecules or ions of the solute.
Energy is released when water molecules bond to the solute molecules or ions.
If it takes more energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes down (endothermic).
If it takes less energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes up (exothermic).
Explanation:
Answer: The 234.74 grams of sample should be ordered.
Explanation:
Let the gram of 114 Ag to ordered be 
The amount required for the beginning of experiment = 0.0575 g
Time requires to ship the sample = 4.2hour = 252 min(1 hr = 60 min)
Half life of the sample =
= 21 min

![\log[N]=\log[N_o]-\frac{\lambda t}{2.303}](https://tex.z-dn.net/?f=%5Clog%5BN%5D%3D%5Clog%5BN_o%5D-%5Cfrac%7B%5Clambda%20t%7D%7B2.303%7D)
![\log[0.0575 g]=\log[N_o]-\frac{0.033 min^{-1}\times 252 min}{2.303}](https://tex.z-dn.net/?f=%5Clog%5B0.0575%20g%5D%3D%5Clog%5BN_o%5D-%5Cfrac%7B0.033%20min%5E%7B-1%7D%5Ctimes%20252%20min%7D%7B2.303%7D)

The 234.74 grams of sample should be ordered.