How many $EDTA$ (ethylenediaminetetraacetic acid) molecules are required to make an octahedral complex with a $Ca^{2+}$ ion?

Which of the following is an example of a hexadentate ligand?

When $1 \ mol$ of the complex $Co(NH_3)_5Cl_3$ is dissolved in water,it yields $3 \ mol$ of ions. When $1 \ mol$ of the same complex reacts with $2 \ mol$ of $AgNO_3$,it produces $2 \ mol$ of $AgCl_{(s)}$. What is the structure of this complex?

Mohr's salt is

The volume (in $mL$) of $0.1 \, M \, AgNO_3$ required for complete precipitation of chloride ions present in $20 \, mL$ of $0.01 \, M$ solution of $[Cr(H_2O)_5Cl]Cl_2$ as silver chloride is $..........$.

Which of the following is the formula of tartar emetic?