The number of optical isomers possible for [Cr(C₂O₄)₃]^3$$-$$ is ____________.

1 mol of an octahedral metal complex with formula MCl₃ . 2L on reaction with excess of AgNO₃ gives 1 mol of AgCl. The denticity of Ligand L is ____________. (Integer answer)

The overall stability constant of the complex ion [Cu(NH₃)₄]²⁺ is 2.1 $$\times$$ 10¹³. The overall dissociations constant is y $$\times$$ 10^$$-$$14. Then y is __________. (Nearest integer)

The ratio of number of water molecules in Mohr's salt and potash alum is ____________ $$\times$$ 10^$$-$$1. (Integer answer)