8. The Dromornis stirtoni is 454 kg. The ostrich is 156 kg. The difference is 298 kg.
9. Th Andean condor is 9 kg. The Eurasian eagle owl is 4.2 kg. The Condor is bigger by 4.8 kg.
10. A truck is way heavier than 2 kg. An orange and mosquito are way lighter than 2 kg. A math book is about 2 kg.
11. A pen would best be found in grams, since it is less than one kg.