N(CuSO₄)=135/{63.5+32.1+4*16.0}=0.846 mol
n(CuSO₄*5H₂O)=135/{63.5+32.1+4*16.0+5*(2*1.0*+16.0)}=0.541 mol
n(H₃PO₄)=135/{3*1.0+31.0+4*16.0}=1.378 mol
n(BaCl₂)=135/{137.3+2*35.5}=0.648 mol
A simple magnetic compass can be used
The (valence) electrons of an atom because they're the most moveable particles of the atom...they are found on the valence shells and can move, unlike the protons and neutrons which are enclosed in the nucleus of the atom.
