When ammonia is added to a cupric salt solution,the deep blue colour is observed; it is due to the formation of

Cobalt $(III)$ chloride forms several octahedral complexes with ammonia. Which of the following will not give a test for chloride ions with silver nitrate at $25 \ ^oC$?

When concentrated sulphuric acid is added slowly to a solution of ferrous sulphate containing nitrate ion,a brown coloured ring is formed. The composition of the ring is

Which of the following is the most stable complex?

$A$ solution containing $2.675 \ g$ of $CoCl_3 \cdot 6NH_3$ (molar mass $= 267.5 \ g \ mol^{-1}$) is passed through a cation exchanger. The chloride ions obtained in the solution are treated with excess $AgNO_3$ to give $4.78 \ g$ of $AgCl$ (molar mass $= 143.5 \ g \ mol^{-1}$). The formula of the complex is $(Ag = 108 \ u)$:

Which of the following complexes has the highest stability at $298 \ K$?