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Hatshy [7]
3 years ago
15

The buildings in this old mine are made of metal. You can see over 100 years, the silver color of the buildings has changed. The

red-brown color is rust. What does this color change tell us about the metal? A) The metal is malleable. B) The metal reacts in the presence of air and water. C) Acid rain has damaged the building over the years. D) The metal is a good conductor of heat and electricity.
Chemistry
2 answers:
Anna11 [10]3 years ago
8 0

Answer:

The correct answer is option B.

Explanation:

4Fe(s)+3O_2(g)\rightarrow 2Fe_2O_3(s)

Iron in presence of moisture reacts with oxygen gas to from iron(III) oxide of red brown color often termed as rust.

Building material used up in min building is metal which which span of time changed its color to rust formation. Therefore this means rust or change in color is due to the iron metal which reacts with oxygen and water present in the air.

vladimir2022 [97]3 years ago
5 0
The correct answer is:  [<span>B]:  "The metal reacts in the presence of air and water." 
____________________________________________________________</span>
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Soloha48 [4]

Answer : The correct option is, (b) 22.5 M

Explanation : Given,

Mass of calcium nitrate tetrahydrate = 266 g

Molar mass of calcium nitrate tetrahydrate  = 236.15 g/mole

Volume of solution = 100cm^3=100mL

Molarity : It is defined as the moles of solute present in one liter of solution.

Formula used :

Molarity=\frac{\text{Mass of calcium nitrate tetrahydrate }\times 1000}{\text{Molar mass of calcium nitrate tetrahydrate }\times \text{volume of solution in ml}}

Now put all the given values in this formula, we get:

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The concentration of nitrate ion = 2\times 11.26M=22.5M

Thus, the concentration of nitrate ion is, 22.5 M

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Answer:

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