Answer : The volume of the cube is, 
Solution : Given,
Density of nickel = 
Number of nickel atoms = 
Molar mass of nickel = 58.7 g/mole
First we have to calculate the moles of nickel.
As,
atoms form 1 mole of nickel
So,
atoms form
moles of nickel
The moles of nickel = 3.321 moles
Now we have to calculate the mass of nickel.


The mass of nickel = 194.94 g
Now we have to calculate the volume of nickel.



Therefore, the volume of the cube is, 
The material which is used as source for commercial production aluminum is bauxite.
The aluminum can be extracted from bauxite ore by the process of Bayer process.
In the Bayer process, bauxite ore is heated in the pressure vessel along with a caustic soda solution (sodium hydroxide) at a temperature between 150 to 200 °C. At this temperatures, the aluminium is dissolved in the solution as sodium aluminate in the extraction process. After separation of the residue by filtering, when the liquid is cooled gibbsite is precipitated and then it is seeded with fine-grained aluminum hydroxide crystals from previous extractions. The precipitation take 7-19 days without the addition of seed crystals.
This extraction process converts the aluminium oxide to soluble sodium aluminate, NaAlO2, which afterward converted into aluminum hydroxide and then into aluminum oxide.
Thus, we concluded that the material which is used as source for commercial production aluminum is bauxite ore.
learn more about ore:
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Answer : The correct option is, (2) Cr (Chromium)
Explanation :
The reactivity series of metal are arranged of the reactivity from the highest to the lowest. Reactivity series is used to determine the products of the single displacement reactions. In the single displacement reaction, the most reactive metal displaces the least reactive metal.
From the given reactivity series we conclude that there are two metal (Mg and Cr) are more reactive metal than the Ni and there are two metal (Pb and Cr) are less reactive metal than the Zn. So, the Cr (Chromium) is the metal which is more active than Ni and less active than Zn.
Hence, the correct option is, (2) Cr
CaO because oxygen have 2 dots and calcium as well
(oxygen valency -2
calcium valncy +2)= CaO
<h2>
Answer:</h2>
In <u>Combination reaction</u>, two or more elements combined to form one compound of different properties.
- C(s) + O2(g) ⇢ CO2(g).
- H2(g) + O2(g) ⇢ H20(l).
In <u>Displacement reation</u>, the high reactive element displaces the low reactive element and formed compound of different properties.
- Fe(s) + CuSo4(aq) ⇢ FeSo4(aq) + Cu(s).
- AgNO3(aq) + Cu(s) ⇢ CuNO3(aq) + Ag(s).