The type isomerism present in nitropentammine chromium $$\left( {{\rm I}{\rm I}{\rm I}} \right)$$ chloride is :

Acetylene does not react with :

For a cell given below


$$ \begin{aligned} \mathrm{Ag}^{+}+\mathrm{e}^{-} & \longrightarrow \mathrm{Ag}; E^{\circ}=x \\\\ \mathrm{Cu}^{2+}+2 e^{-} & \longrightarrow \mathrm{Cu}{;} E^{\circ}=y \end{aligned} $$

$$ E^{\circ} \text { cell is } $$ :

The period of $${\sin ^2}\theta $$ is