
The reactivity of halides towards the S$_N$1 mechanism depends on the stability of the carbocation intermediate formed during the reaction:
Compound A forms a benzyl carbocation, which is highly stable due to resonance.
Compound B forms a primary carbocation, which is less stable but reacts due to iodine's leaving group strength.
Compound C forms a tertiary carbocation, which is very stable and reactive.
Compound D forms a primary carbocation, less stable but reacts due to bromine's moderate leaving group strength.
Thus, the halogens are ordered as per the leaving group stability in S$_N$1.
Calculate the potential for half-cell containing 0.01 M K\(_2\)Cr\(_2\)O\(_7\)(aq), 0.01 M Cr\(^{3+}\)(aq), and 1.0 x 10\(^{-4}\) M H\(^+\)(aq).

A square loop of sides \( a = 1 \, {m} \) is held normally in front of a point charge \( q = 1 \, {C} \). The flux of the electric field through the shaded region is \( \frac{5}{p} \times \frac{1}{\varepsilon_0} \, {Nm}^2/{C} \), where the value of \( p \) is: