Find number of basic radicals among the following cations, which can form soluble complex on adding excess of `NH_(4) ` solution.
`Cd^(2+)(aq.),Pb^(2+)(aq.),Ni^(2+)(aq.),Mn^(2+)(aq.),Zn^(2+)(aq.),Ag^(+)(aq.),Hg^(2+)(aq.),Fe^(3+)(aq.),Mg^(2+)(aq.)`

Find out the number of cation (s) which form(s) black ppt. (soluble in hot and dilute HNO_(3) ) on passing H_(2)S gas into their salt solution? Mg^(2+)(aq.)Cu^(2+)(aq.),Ba^(2+)(aq.),Fe^(3+)(aq.),Ag^(+)(aq.),Al^(3+)(aq.),Hg^(2+)(aq.),Pb^(2+)(aq.),Mn^(2+)(aq.)

Find out total number of cation(s) that produce precipitate with aqueous solution of Na_(2)CO_(3) . Cu^(2+)(aq.),Mg^(2+)(aq.),Fe^(3+)(aq.),Pb^(2+)(aq.),Al^(3+)(aq.),Hg^(2+)(aq.),Zn^(2+)(aq.),NH_(4)^(+)(aq.),Cs^(+)(aq.)

Find total number of metal cations which are ppted as metal sulphide on passing H_(2)S gas through metal salt solution. Pb^(2+)(aq.)," "Mn^(2+)(aq.)," "Sn^(2+)(aq.)," "Cr^(3+)(aq.)," "Mg^(2+)(aq.)," "Hg^(2+)(aq.)," "Cu^(2+)(aq.)," "Ag^(+)(aq.)," "Al^(3+)(aq.)," "Ni^(2+)(aq.)

Based on the standard reduction potentials above, which reaction(s) is (are) spontaneous? (P) Cr^(2+)(aq)+Fe^(3+)(aq)rarrCr^(2+)(aq)+Fe^(2+)(aq) (Q) Cu^(2+)(aq)+Fe^(2+)(aq)rarrCu^(2+)(aq)+Fe^(3+)(aq)

In the following reaction, which is the species being oxidised ? 2Fe_((aq))^(3+)+2I_((aq))^(-) to I_(2(aq))+2Fe_((aq))^(2+)