\(n_{H_2SO_4}=0.3\cdot1=0.3\left(mol\right)\)
\(2NaOH+H_2SO_4\rightarrow Na_2SO_4+H_2O\)
\(0.6...............0.3...............0.3\)
\(V_{dd_{NaOH}}=\dfrac{0.6}{1}=0.6\left(l\right)=600\left(ml\right)\)
\(C_{M_{Na_2SO_4}}=\dfrac{0.3}{0.3+0.6}=0.33\left(M\right)\)