The best idea to solve this question is to convert all in same unit i.e. grams.
1 Gg = 10^9 g
100 g = 10^2 g
50 cg = 50*10^-2 g = 0.5 g
1 kg = 1000 g
1 cg = 0.01 g
1 dg = 0.1 g
50 mn ng = 50 * 10^6 * 10^-9 gram = 5* 10 ^-2 g = 0.5g
So, the correct order is 1 Gg > 1 kg > 100 g > 50 cg = 50 mn ng > 1 dg > 1 cg
