<span>CO + H2O --> CO2 + H2, C is oxidized, H reduced, Oxygen is spectator ion.</span><span />
Moles of MgF₂ : 1.2 x 10⁻⁴
<h3>Further explanation</h3>
Maybe the complete question is like this
<em>A student prepares 100. mL of a saturated solution of MgF2 by adding 0.50 g of solid MgF2 to 100. mL of distilled water at 25°C and stirring until no more solid dissolves. (Assume that the volume of the undissolved MgF2 is negligibly small.) The saturated solution is analyzed, and it is determined that [F−] in the solution is 2.4 × 10−3 M. </em>
<em />
The dissociation reaction of MgF₂
MgF₂(s)⇒ Mg²⁺(aq)+2F⁻(aq)
mol ratio MgF₂ : F⁻ = 1 : 2
mol of F⁻ in 100 ml solution :

mol MgF₂ :

The chemical element of atomic number 86, a rare radioactive gas belonging to the noble gas series.
Answer:
Explanation:
In the following reaction we have shown an example of aromatic substitution reaction .
C₆H₆ + RCl = C₆H₅R + HCl
This reaction takes place in the presence of catalyst like AlCl₃ which is a lewis acid .
First of all formation of carbocation is made as follows .
RCl + AlCl₃ = R⁺ + AlCl₄⁻
This R⁺ is carbocation which is also called electrophile . It attacks the ring to get attached with it .
C₆H₆ + R⁺ = C₆H₅R⁺H.
The complex formed is unstable , though it is stabilized by resonance effect . In the last step H⁺ is kicked out of the ring . The driving force that does it is the steric hindrance due to presence of two adjacent group of H and R⁺ at the same place . Second driving force is attack by the base AlCl₄⁻ that had been formed earlier . It acts as base and it extracts proton ( H⁺ ) from the ring .
C₆H₅R⁺H + AlCl₄⁻ = C₆H₆ + AlCl₃ + HCl .
The formation of a stable product C₆H₆ also drives the reaction to form this product .