Write the chemical formula of the main product obtained when ethanol is heated with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ at $413 \mathrm{K}$.

Explain the ideal solution on the basis of the following points –

(A) Change in enthalpy

(B) Change in Volume

Explain the reason for the value of order of reaction is $1$. Why the value of molecularity is $2$ in the above reaction.

Show that in a first order reaction, time required for completion of $99.9\%$ is $10$times of half-life $\left({\mathrm{t}}_{1/2}\right)$ of the reaction.

Explain the following properties exhibiting by transition elements -

(A) Variable oxidation state

(B) Catalytic property