Given below are two statements :

Statement I: Both $$[\mathrm{Co}(\mathrm{NH}_3)_6]^{3+}$$ and $$[\mathrm{CoF}_6]^{3-}$$ complexes are octahedral but differ in their magnetic behaviour.

Statement II: $$[\mathrm{Co}(\mathrm{NH}_3)_6]^{3+}$$ is diamagnetic whereas $$[\mathrm{CoF}_6]^{3-}$$ is paramagnetic.

In the light of the above statements, choose the correct answer from the options given below:

Given below are two statements :

Statement I : $$[\mathrm{Co}(\mathrm{NH}_3)_6]^{3+}$$ is a homoleptic complex whereas $$[\mathrm{Co}(\mathrm{NH}_3)_4 \mathrm{Cl}_2]^{+}$$ is a heteroleptic complex.

Statement II : Complex $$[\mathrm{Co}(\mathrm{NH}_3)_6]^{3+}$$ has only one kind of ligands but $$[\mathrm{Co}(\mathrm{NH}_3)_4 \mathrm{Cl}_2]^{+}$$ has more than one kind of ligands.

In the light of the above statements, choose the correct answer from the options given below.

Select the element (M) whose trihalides cannot be hydrolysed to produce an ion of the form [M(H$$_2$$O$$_6$$]$$^{3+}$$

Which of the following forms a set of complex and a double salt, respectively?