What is the formal charge on 'N' atom in

ion?

Identify the product 'B' in the following series of reactions.

$$\mathrm{CH_3COOH+CH_3CH_2OH}$$ $$\stackrel{\mathrm{H}^{+}}{\rightleftharpoons} A \xrightarrow[\mathrm{Ni} / \mathrm{Pd}, \Delta]{\mathrm{H}_2}$$ B

The solubility of sparingly soluble salt $$\mathrm{AB}_2$$ is $$1.0 \times 10^{-4} \mathrm{~mol} \mathrm{~dm}^{-3}$$. What is it's solubility product?

Which element from following in +3 oxidation state forms colourless compounds?