\(a,H_2SO_4+2NaOH\rightarrow Na_2SO_4+2H_2O\\ n_{H_2SO_4}=1.0,4=0,4\left(mol\right)\\ n_{NaOH}=0,4.2=0,8\left(mol\right)\\ b,V_{ddNaOH}=\dfrac{0,8}{0,5}=1,6\left(l\right)\\ c,n_{Na_2SO_4}=n_{H_2SO_4}=0,4\left(mol\right)\\ V_{ddNa_2SO_4}=0,4+1,6=2\left(l\right)\\ C_{MddNa_2SO_4}=\dfrac{0,4}{2}=0,2\left(M\right)\)