Answer:
1. Hydrogen
Explanation:
These planets contain liquid hydrogen in their interior, while the earth has liquid iron in it.
When liquid hydrogen is in tremendous pressure enviroments, the electrons that make up each atom of this element end up "jumping" to other atoms. These "jumps" allow liquid hydrogen to behave like a metal.
In addition, with the constant energy released by the nucleus of planets like Jupiter and Saturn, as well as their rotations, the liquid hydrogen receives induction of currents, giving rise to extremely powerful magnetic fields.
0.000735 in scientific notation is 7.35 x 10^-4
Mass is related to weight. It measures the resistance of the substance to acceleration when a net force is applied.
Therefore: armful of lead has more mass
volume measures the amount of 3-dimensional space that an object occupies.
Therefore: kilogram of feather has more volume as it is less dense.
density is the mass per unit volume. Since armful of lead has more mass than a handful of feathers, while kilogram of feather has more volume than a kilogram of lead.
Therefore: kilogram of lead has higher density.
B, radon is correct. Interestingly, it often collects in basements from radioactive decay of rocks such as granite that contain uranium. Because it is an unreactive noble gas and because it is denser than air it sits in basements and must be pumped out. It collects in human lungs and is the second leading cause of lung cancer behind smoking.