In which of the following reactions is the $Saytzeff$ alkene the major product?

Which best describes the product of the following reaction?
$Ph-C(CH_3)(Br)-CD_3 \xrightarrow{K^+ t-BuO^-, E_2} \text{product}$

Compound $A$ with molecular formula $C_4H_9Br$ is treated with aqueous $KOH$ solution. The rate of this reaction depends upon the concentration of compound $A$ only. When another optically active isomer $B$ of this compound was treated with aqueous $KOH$ solution,the rate of reaction was found to be dependent on the concentration of both the compound and $KOH$.
$(i)$ Write down the structural formula of both compounds $A$ and $B$.
$(ii)$ Out of these two compounds,which one will be converted to the product with inverted configuration?

The reaction of ethyl bromide with lead-sodium alloy gives ......... .

$A$ bottle containing $C_6H_5I$ and $C_6H_5CH_2I$ has lost its label. To identify them,samples $A$ and $B$ are taken in separate test tubes and boiled with $NaOH$ solution. Finally,the solution in each test tube is acidified with dilute $HNO_3$ and then a few drops of $AgNO_3$ solution are added. Substance $B$ gives a yellow precipitate. Which statement is correct for this process?

Observe the following reactions. The order of reactivity of $x, y, z$ towards $S_{N}1$ reaction is: