Arrange the following compounds in decreasing order of reactivity for nucleophilic substitution reaction:
$(I)$ $CH_3-CH_2-OSO_2CF_3$
$(II)$ $CH_3-CH_2-OTs$
$(III)$ $CH_3-CH(OH)-CH_3$
$(IV)$ $C_6H_5-CH(OH)-CH_3$

What are ambident nucleophiles? Explain with an example.

What is the principal product of the following reaction?
$CH_3-CH(Br)-CH_2-CH_2-CH(Cl)-CH_3 + NaN_3 \rightarrow \text{Product}$

Which of the following statements is incorrect for a bimolecular nucleophilic substitution reaction $(S_{N}2)$?

$CH_3-CH_2-C(Br)(CH_2CH_3)-CH_2(CH_2CH_2CH_3) \xrightarrow{alc. KOH} (A)$ (major)
$n-Pr = n-propyl$
Product $(A)$ is

Consider the following reaction:
$CH_3-CH_2-CH(Br)-CH_3 \xrightarrow{alc. KOH, \Delta} CH_3-CH_2-CH=CH_2 (I) + CH_3-CH=CH-CH_3 (II)$
Which of the following statements are correct?
$a.$ $I$ is the major product of the reaction
$b.$ $II$ is the major product of the reaction
$c.$ Formation of $I$ is in accordance with Saytzeff's rule
$d.$ $II$ is more stable because it is more substituted