Which of the following is an example of a neutral oxide?

Among the following series of transition metal ions,the one where all metal ions have $3d^2$ electronic configuration is

The position vectors of $P$ and $Q$ are respectively $\overrightarrow{a}$ and $\overrightarrow{b}$. If $R$ is a point such that $\overrightarrow{PR}=5 \overrightarrow{PQ}$, then the position vector of $R$ is

If $X$ is a Poisson variate such that $P(X=1)=P(X=2)$, then $P(X=4)$ is equal to

$AgNO_3 \xrightarrow{\Delta} (W) + (X) + O_2$
$(X) + H_2O \to HNO_2 + HNO_3$
$(W) + HNO_3 \to (Y) + NO + H_2O$
$(Y) + Na_2S_2O_3 (\text{excess}) \to (Z) + NaNO_3$
Identify $(W)$ to $(Z)$.

$A$ ball falls from a height $h$ and rebounds after striking the floor. The coefficient of restitution is $e$. The total distance covered before it comes to rest is