Which of the following can give ${\mathrm{E}}_{1\mathrm{cb}}$ reaction?

Suggest mechanism for the following: 

Suggest mechanism for the following:

Complete the following equation:

Complete the following equation:

Complete the following equation:

${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{OH} \stackrel{?}{\to }{\mathrm{CH}}_3\mathrm{CH}={\mathrm{CH}}_2$

Complete the following equation:

Which compound of each pair is more reactive towards the reaction given against each?

 (addition of $\mathrm{HBr}$)

Which compound of each pair is more reactive towards reaction given against each?

 (addition of $\mathrm{HCl}$)