Which alloy exhibits the property of shape memory?

Give the preparation of potassium dichromate and state its uses.
Give the structures of chromate and dichromate ions. How can chromates and dichromates be interconverted?
Give the chemical reactions showing the oxidizing nature of potassium dichromate.

Which among the following statements is incorrect for manganate and permanganate ions?

$KMnO_4$ is the oxo-salt of the acid of which of the following oxides?

$Cr_2O_7^{2-} \underset{Y}{\overset{X}{\longleftrightarrow}} 2CrO_4^{2-}$,$X$ and $Y$ are respectively

When an oxide of manganese $(A)$ is fused with $KOH$ in the presence of an oxidising agent and dissolved in water,it gives a dark green solution of compound $(B)$. Compound $(B)$ disproportionates in neutral or acidic solution to give purple compound $(C)$. An alkaline solution of compound $(C)$ oxidises potassium iodide solution to a compound $(D)$ and compound $(A)$ is also formed. Identify compounds $A$ to $D$ and also explain the reactions involved.