1-It has to be 3 Fe and not Fe3.
2-The oxygens aren't balanced
Balanced equation:
3Fe+4H2O---->Fe3O4+4H2
6.02 x10^23 atom
3.5g x 1mol/63.55g Cu x 6.02 x 10^23/ 1mol=
3.32 x 10^22 atoms
KCI is not a covalent compound, it is an ionic compound.
A covalent compound is one in which each of the atoms involved contribute a specific number of electrons for sharing in order to from stable compound while an ionic compound is a compound formed when one atom donates electron to the other atom in the compound, in order to attain stability. The compounds given in options A, B and D shared electrons while in KCl, potassium donates an electron to chlorine.
Hmm, friction maybe? I guess it depends on how fast she stopped?
