When $MgSO_4$ is treated with $NH_4OH$ and $Na_2HPO_4$,a white crystalline solid is formed. What is its formula?

Which ions can be separated using concentrated $NaOH$?

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	$(d)$ $Na_2[Fe(CN)_5NO]$

The reagent used for the identification of $Ni^{2+}$ ions is .....

The pair$(s)$ of ions where $BOTH$ the ions are precipitated upon passing $H_2S$ gas in the presence of dilute $HCl$,is(are):
$(A) Ba^{2+}, Zn^{2+}$
$(B) Bi^{3+}, Fe^{3+}$
$(C) Cu^{2+}, Pb^{2+}$
$(D) Hg^{2+}, Bi^{3+}$

Lead sulfate is soluble in which of the following?