Hydrogen peroxide acts both as an oxidising and as a reducing agent in alkaline solution towards certain first row transition metal ions. Illustrate both these properties of H₂O₂ using chemical equations.

Interpret the non-linear shape of H₂S molecule and non-planar shape of PCl₃ using valence shell electron pair repulsion (VSEPR) theory. (Atomic numbers : H = 1, P = 15, S = 16, Cl = 17)

The geometry and the type of hybrid orbital present about the central atom in BF₃ is

Decrease in atomic number is observed during