The mantle layer is more dense closest to the core.
<span>You have to use an activity series and then predict which metal by itself will replace the metal inside of the compound. These all appear to be single replacement reactions.</span>
Data:
Arsenic Molar Mass = 74,9216 ≈ 75 u (<span>atomic mass unit)</span>
Solving:
1 mole of arsenic → 75g ------------ 6,02*10²³ molecules
..................................X -------------- 1 molecule
6,02*10²³X = 75