_____ is used in the estimation of iodine number of fats and oils.

$$\begin{gathered} {\text{Cl}}_{\text{2}}\text{+NaOH }\stackrel{\text{–NaCl} \\ -{\text{H}}_{\text{2}}\text{O}}{\to }\text{ X} \\ \text{(cold and dilute)} \end{gathered}$$

$$\begin{gathered} {\text{Cl}}_{\text{2}}\text{+NaOH }\stackrel{\text{–NaCl} \\ -{\text{H}}_{\text{2}}\text{O}}{\to }\text{ Y} \\ \text{(hot and concentrated)} \end{gathered}$$

In these reactions, $\mathrm{X}$ and $\mathrm{Y}$ are _____ respectively.