Question

A reddish brown developed a green colored solid x

Answer 1

A reddish brown vessel developed a green coloured solid X when left open in air for a long time. When reacted with dilute H2SO4 it forms a blue coloured solution along with brisk effervescence due to colourless and odourless gas Z. X decomposes to form black coloured oxide Y of a reddish brown metal along with gas Z. Identify X, Y and Z.