Question

Consider the following changes
$M\left(s\right)⟶M\left(g\right)$ ...(1)
$M\left(g\right)⟶M^{2+}\left(g\right)+2e^{-}$ ....(2)
$M\left(g\right)⟶M^{+}\left(g\right)+e^{-}$ ....(3)
$M^{+}\left(g\right)⟶M^{2+}\left(g\right)+e^{-}$ ...(4)
$M\left(g\right)⟶M^{2+}\left(g\right)+2e^{-}$ ...(5)
The second ionisation energy of $M$ could be determined from the energy values associated with:

• A. $1+2+4$
• B. $1+5-3$
• C. $2+3-4$
• D. $5-3$

Answer 1

The correct option is D $5-3$

The amount of energy required to take out an electron from the monopositive cation is called second ionisation energy
$M\left(g\right)⟶M^{2+}\left(g\right)+2e^{-}$ (v)
$M\left(g\right)⟶M^{+}\left(g\right)+e^{-}$ (iii)
On subtracting equation (iii) from equation (v) we get,
$M⟶M^{2+}+e^{-}$.