Rest and motion are relative term give reason

Ithink the answer is pollution in the air steel made of iron and carbon

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water

The correct answer is "hydrogen".

Answerhave membrane-bound organelles;