The correct option is C 6.023×1022 atoms
Gram molar mass of Na2CO3=2×23+12+3×16=106 g
106 g of Na2CO3 = 1 mol
5.3 g of Na2CO3 = 1×5.3106=0.05 mol
Now,1 mol of Na2CO3 contains = 2×6.023×1023 sodium atoms
Therefore, 0.05 mol of Na2CO3 contains = 0.05×2×6.023×1023 sodium atoms
=6.023×1022 Na atoms