Explain the reason for the following:
A primary alkylhalide, RX, reacts with KCN to give an alkyl cyanide and with AgCN to give an alkyl isocyanide as the major, product.

Explain the reason for the following:
Tertiary butyl iodide forms tertiary butyl alcohol with water, but with an alkali solution, it yields isobutylene (2-methyl propene).

Explain the reason for the following:

Unlike the chlorine atom in CH₃Cl, that in chlorobenzene, C₆H₅Cl is not easily replaced by the -OH group.

Explain the reason for the following:

Halogens delocalize electrons in the benzene ring in the order F > Cl > Br > I.