HW of week $1$

$2.$ Draw all the plausible resonance structures for the following compounds$/$ions$.$

a$.$

b$.$

c$.$

$3.$ For the following reactions, predict major product$($s$),$ include stereochemistry, and identify the reaction mechanism $(S_{N}1$ or $S_{N}2).$

a$.$

b$.$

d$.$