Calculate the molarity of the solution obtained on mixing 100 mL of 0.1 M H2SO4 with 50 mL of 0.1 M NaOH.

when two solutions of different molarity and volumes are mixed to form a new solution of new molarity (say M) then, you can use the molarity equation,,
M1V1 + M2V2 = M(V1 + V2)
where M1 is the molarity of first solution= 0.1 M , M2 is the molarity of second solution = 0.1 M , V1 is the volume of first solution = 100ml = 100/1000 = 0.1 L , V2 is the volume of second solution = 50ml = 50/1000= 0.05 L and M is the molarity of new solution.
now, substituting the all values in the equation, we have,
M1V1 + M2V2 = M(V1 + V2)
0.1 x 0.1 + 0.1 x 0.05 = M(0.1 + 0.05)
0.01 + 0.005 = M x 0.15
0.015 = M x 0.15
M = 0.015/0.15 = 0.1
Hence the molarity of the new solution is 0.1M