A block of ice floats on a liquid of density 1.2 in a beaker then level of liquid when ice completely melt 

The volume of liquid displaced by floating ice ${\mathrm{V}}_{\mathrm{D}}=\frac{\mathrm{M}}{{\mathrm{\sigma }}_{\mathrm{L}}}$ 
Volume of water formed by melting ice,  ${\mathrm{V}}_{\mathrm{F}}=\frac{\mathrm{M}}{{\mathrm{\sigma }}_{\mathrm{W}}}$
If ${\mathrm{\sigma }}_1>{\mathrm{\sigma }}_{\mathrm{W}},$ then, $\frac{\mathrm{M}}{{\mathrm{\sigma }}_{\mathrm{L}}}<\frac{\mathrm{M}}{{\mathrm{\sigma }}_{\mathrm{W}}}$ i.e. ${\mathrm{V}}_{\mathrm{D}}<{\mathrm{V}}_{\mathrm{F}}$ 
i.e. volume of liquid displaced by floating ice will be lesser than water formed and so the level of liquid will rise.