Identify the element from following such that the last electron is placed in $(\mathrm{n}-1) \mathrm{d}$ orbital.

Which transition series includes elements Co and Mo respectively?

Rate law for the reaction,

$$ \mathrm{C}_2 \mathrm{H}_5 \mathrm{I}_{(\mathrm{g})} \longrightarrow \mathrm{C}_2 \mathrm{H}_{4(\mathrm{~g})}+\mathrm{HI}_{(\mathrm{g})} \text { is } \mathrm{r}=\mathrm{k}\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{I}\right] $$

What is the order and molecularity of this reaction?

Find the mass of potassium chlorate required to liberate $5.6 \mathrm{dm}^3$ of oxygen gas at STP? (molar mass of $\mathrm{KClO}_3=122.5 \mathrm{~g} / \mathrm{mol}$ )