Consider the following sequence of reactions:
$M^{2+}(aq.)$ $\xrightarrow{NH_4Cl(s) + (NH_4)_2CO_3 \, sol.} Q \downarrow$ $\xrightarrow[\text{Followed by addition of } (NH_4)_2C_2O_4]{CH_3COOH} R \downarrow$
Which of the following cations can form precipitate $Q$ but does not form precipitate $R$?

When $MgSO_4$ reacts with $NH_4OH$ and $Na_2HPO_4$,it forms a white crystalline substance. What is the formula of that substance?

An aqueous solution contains the ions as $Hg_2^{2+}$,$Hg^{2+}$,$Pb^{2+}$,and $Cd^{2+}$. The addition of dilute $HCl$ $(6 \ N)$ precipitates:

The correct option$(s)$ to distinguish nitrate salts of $Mn^{2+}$ and $Cu^{2+}$ taken separately is (are):
$(A)$ $Mn^{2+}$ shows the characteristic green colour in the flame test
$(B)$ Only $Cu^{2+}$ shows the formation of precipitate by passing $H_2S$ in acidic medium
$(C)$ Only $Mn^{2+}$ shows the formation of precipitate by passing $H_2S$ in faintly basic medium
$(D)$ $Cu^{2+}/Cu$ has higher reduction potential than $Mn^{2+}/Mn$ (measured under similar conditions)

Which of the following sulphates is insoluble in water?

Match column-$I$ and column-$II$ with correct relation:

Column-$I$	Column-$II$
$(i)$ Blood like red colour	$(a)$ $Fe_4[Fe(CN)_6]_3$
$(ii)$ Sodium nitroprusside	$(b)$ $(NH_4)_2MoO_4$
$(iii)$ Ammonium molybdate	$(c)$ $[Fe(SCN)]^{2+}$
$(iv)$ Ferri-ferro cyanide	$(d)$ $Na_2[Fe(CN)_5NO]$