Which one of the carbocations from the following is most stable?

The product $(\mathrm{A})$ formed in the following reaction sequence is

$\mathrm{K}_{\mathrm{sp}}$ for $\mathrm{Cr}(\mathrm{OH})_3$ is $1.6 \times 10^{-30}$. What is the molar solubility of this salt in water?

Which of the following linear combination of atomic orbitals will lead to formation of molecular orbitals in homonuclear diatomic molecules [internuclear axis in $z$-direction] ?

A. $2 \mathrm{p}_{\mathrm{z}}$ and $2 \mathrm{p}_{\mathrm{x}}$

B. 2 s and $2 \mathrm{p}_{\mathrm{x}}$

C. $3 d_{x y}$ and $3 d_{x^2-y^2}$

D. 2 s and $2 \mathrm{p}_{\mathrm{z}}$

E. $2 p_z$ and $3 d_{x^2-y^2}$

Choose the correct answer from the options given below: