Which of the following is a double salt?

Which of the following is an example of a homoleptic complex?

$A$ complex of platinum,ammonia,and chloride produces four ions per molecule in the solution. Which structure is consistent with this observation?

In the complex $K[Cr(H_2O)_2(C_2O_4)_2] \cdot 3H_2O$,the oxidation state and coordination number of the central metal ion are . . . . . . and . . . . . . respectively.

Which type of addition compound retains its identity in solution?

Given below are two statements :
Statement $I$ : $[Co(NH_3)_6]^{3+}$ is a homoleptic complex whereas $[Co(NH_3)_4 Cl_2]^{+}$ is a heteroleptic complex.
Statement $II$ : Complex $[Co(NH_3)_6]^{3+}$ has only one kind of ligands but $[Co(NH_3)_4 Cl_2]^{+}$ has more than one kind of ligands.
In the light of the above statements,choose the correct answer from the options given below.