The stabilization of coordination compounds due to chelation is called the chelate effect. Which of the following is the most stable complex species?

Which ion in excess $NaOH$ does not form a soluble complex?

$A$ first row transition metal $(M)$ does not liberate $H_{2}$ gas from dilute $HCl$. $1 \ mol$ of aqueous solution of $MSO_{4}$ is treated with excess of aqueous $KCN$ and then $H_{2}S_{(g)}$ is passed through the solution. The amount of $MS$ (metal sulphide) formed from the above reaction is . . . . . . $mol$.

When $CuSO_4$ solution in water is treated with concentrated $HCl$,it turns:

Silver chloride dissolves in excess of $NH_4OH$. The cation present in this solution is

Match List-$I$ (Molar Conductivity) with List-$II$ (Complex Formula) and select the correct option:

List-$I$ (Conductivity)	List-$II$ (Formula)
$A. \ 229$	$i. \ [Pt(NH_3)_3Cl_3]Cl$
$B. \ 97$	$ii. \ [Pt(NH_3)_4Cl_2]Cl_2$
$C. \ 404$	$iii. \ [Pt(NH_3)_5Cl]Cl_3$
$D. \ 523$	$iv. \ [Pt(NH_3)_6]Cl_4$