Au

Ag

Hg

Cu

It is liquid at room temperature.

It is dense.

It does not readily form Hg²⁺.

It is a good conductor of electricity.

${\rm{ZnO}}$

${\rm{HgO}}$

${\rm{A}}{{\rm{g}}_2}{\rm{O}}$

${\rm{CuO}}$

Washing it carefully with soap and water

Soaking it overnight in salt water

Polishing it with silver polish

Heating it gently in a fume cupboard

HgS

PbS

CuS

CdS

Ag + Cu

Ag + Zn

Cu + Zn

Cu + Sn

${\rm{Cu}}{\left( {{\rm{OH}}} \right)_2}.2{\rm{CuC}}{{\rm{O}}_3}$

${\rm{CuS}}{{\rm{O}}_4}.3{\rm{Cu}}{\left( {{\rm{OH}}} \right)_2}$

${\rm{Cu}}{\left( {{\rm{OH}}} \right)_2}.{\rm{CuC}}{{\rm{O}}_3}$

${\rm{CuFe}}{{\rm{S}}_2}$

$Mn^{2+}$

$Fe^{2+}$

$Co^{2+}$

$Ni^{2+}$

It has a completely filled $s$-orbital.

It has a small atomic size.

It has a completely filled $d$-orbital that prevents $d - d$ overlapping of orbitals.

It has a completely filled $d$- orbital that causes $d - d$ overlapping.

Hg

$\rm{Hg}_2\rm{Cl}_2$

$\rm{SnCl}_4$

$\rm{SnCl}_2$

Red lead

Ammoniacal silver nitrate

Ammoniacal ${\rm{AgN}}{{\rm{O}}_3} +$red lead

Ammoniacal ${\rm{AgN}}{{\rm{O}}_3} +$red lead + HCHO