Which of the following symbols represent heat of reaction at constant volume?

For the reaction,

$$3 \mathrm{I}_{\mathrm{(aq.)}}^{-}+\mathrm{S}_2 \mathrm{O}_{8(\mathrm{aq.})}^{2-} \longrightarrow 2 \mathrm{SO}_{4(\mathrm{aq.})}^{2-}+\mathrm{I}_{3(\mathrm{aq.})}^{-}$$

rate of formation of $\mathrm{SO}_{4(\mathrm{aq.})}^{2-}$ is $0.044 \mathrm{~mol} \mathrm{~dm}^{-3} \mathrm{~s}^{-1}$.

Calculate rate of consumption of $\mathrm{I}_{(\mathrm{aq.})}^{-}$.

Identify a ligand having two donor atoms but uses a pair of electrons of either donor atom to form coordinate bond.

Which of the following solutions on complete dissociation exhibits maximum elevation in boiling point?