Why is $CCl_{4}$ added in the bromination of an alkene?

Write about ozonolysis of alkene.

Consider the following reactions. What is $A$?
| Reaction | Observation |
| :--- | :--- |
| $A \ (C_7H_{14}) \xrightarrow{\text{ozonolysis}} B + C$ | |
| $B \xrightarrow{I_2 + NaOH, \Delta} \text{yellow ppt}$ | |
| $B \xrightarrow{Ag_2O, \Delta} \text{silver mirror}$ | |
| $C \xrightarrow{I_2 + NaOH, \Delta} \text{no yellow ppt}$ | |
| $C$ $\xrightarrow{LiAlH_4} D$ $\xrightarrow{\text{anhydrous } ZnCl_2, \text{conc. } HCl} \text{white turbidity within 5 minutes}$ | |

Final product formed on reduction of glycerol by hydroiodic acid is

The product obtained when $2-$methylpropan$-2-$ol is treated with alumina $(Al_2O_3)$ at $423 \ K$ is

Identify the type of the given reactions:
$(a) \ CH_3CH_2OH \xrightarrow[\Delta]{\text{Conc. } H_2SO_4} CH_2 = CH_2 + H_2O$
$(b) \ CH_2BrCH_2Br + Zn \xrightarrow{\Delta} CH_2 = CH_2 + ZnBr_2$
$(c) \ CH_3CHBr - CH_2Br + Zn \xrightarrow{\Delta} CH_3CH = CH_2 + ZnBr_2$
$(d) \ RC \equiv CR' + H_2 \xrightarrow{Na, \text{liquid } NH_3} RCH = CHR'$
$(e) \ CH_3CH_2Cl + KOH \xrightarrow{\text{ethanol, } KOH} CH_2 = CH_2 + KCl + H_2O$