The colour of $Mg(OH)_2$ precipitate formed when it is precipitated in the presence of magneson reagent is

Compound $X$ is tested and the results are shown in the table.

Test	Result
Aqueous $NaOH$ is added, then heated gently.	Gas given off which turns damp red litmus paper blue.
Dilute $HCl$ is added.	Effervescence, gas given off which turns lime water milky and acidified $K_2Cr_2O_7$ paper green.

Which ions are present in compound $X$?

Which of the following cations does not give a precipitate with $H_2S$ in a neutral medium?

Aqueous solution of Mohr's salt gives the test of which ions?

$A$ solution is prepared by mixing a concentrated solution of $Co(NO_3)_2$ with a concentrated solution of $NaNO_2$ in $50\%$ acetic acid. $A$ solution of a salt containing metal $M$ is added to the mixture, and a yellow precipitate is formed. Metal $M$ is:

Match List-$I$ with List-$II$:

List-$I$ (Ion)	List-$II$ (Group Number in Cation Analysis)
$A. Co^{2+}$	$I. Group-I$
$B. Mg^{2+}$	$II. Group-III$
$C. Pb^{2+}$	$III. Group-IV$
$D. Al^{3+}$	$IV. Group-VI$

Choose the correct answer from the options given below: