upon mixing equal volume of 0.1M HCl and 0.2 M H2SO4 the concentration of H+ in the resulting solution is

Since they are present in equal volume therefore we can take the volume as 1 litre.
Now,  total no. of moles of H = molarity x volume x no. of moles of H present in compound
For HCl= 0.1x1x1=0.1
For H2SO4 =0.2x1x2 =0.4
Molar concentration of H= no. of moles/total volume
                                       =0.1+0.4/2
                                       =0.5/2
                                        =0.25
so the concentration of H in the resulting solution is 0.25.