A compound has the empirical formula ${\mathrm{CoCl}}_3.5{\mathrm{NH}}_3$. When an aqueous solution of this compound ii mixed with excess silver nitrate, 2 mol of AgCl precipitates per mol of compound. On reaction with excess HCl, no ${\mathrm{NH}}_4^{+}$ is detected. Hence it is

• A

  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{Cl}}_2\right]\mathrm{Cl}$

• B

  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\mathrm{Cl}\right]{\mathrm{Cl}}_2$

• C

  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{Cl}}_3\right]$

• D

  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]\mathrm{Cl}.{\mathrm{NH}}_3$