Answer:
C. 0.20 M Mg ion & 0.40 M Cl ion
Explanation:
MgCl₂ is a ionic salt which is dissociated as this
MgCl₂ → Mg²⁺ + 2Cl⁻
First of all, we have a solution of 200 mL, with [MgCl₂] = 0.6M
Molarity . volume = moles.
0.6 mol/l . 0.2l = 0.12 mol
MgCl₂ → Mg²⁺ + 2Cl⁻
0.12mol 0.12 0.24
This moles are also in 400mL of water, so the new concentration is
[Mg²⁺] = 0.12 m/0.6L = 0.2M
[Cl⁻] = 0.24 m/0.6L = 0.4M
Remember we initially have 200mL and then, we add 400 mL, so we supose aditive volume. (600mL)
Atomic radius atomic number ionization energy and then electronegativity

The 2 in front of
in
is <u>Coefficient.</u>
_____________________________
The
after
in the same equation is <u>sub </u><u>script</u><u>.</u>
_____________________________
There are two atoms of
in 
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Total density of filled ball with nitrogen gas: 
The relationship between mass and volume can be easily determined using density; for example, the mass of a body is equal to its volume multiplied by the density (M = Vd), whereas the volume is equal to the mass divided by the density (V = M/d). The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air. Density of the evacuated ball D = 0.214 g/L
Density of nitrogen gas = 
Mass of the nitrogen gas : 
Learn more about Mass and Density here:
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441 g CaCO₃ would have to be decomposed to produce 247 g of CaO
<h3>Further explanation</h3>
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Decomposition of CaCO₃
CaCO₃ ⇒ CaO + CO₂
mass CaO = 247 g
mol of CaO(MW=56 g/mol) :

From equation, mol ratio CaCO₃ : CaO = 1 : 1, so mol CaO :

mass CaCO₃(MW=100 g/mol) :
