Since the beaker was heated we can asume that only magnesium cloride is left in the beaker, therfore the difference between the beaker with magnesium chloride and the empty beaker give the mass of magnisium chloride:
I’m not too sure I hope someone answers for you
Im pretty sure it would be d.
Substance P replaces X in the compound XY
this is the characteristic of decomposition reaction
In an experiement things that are changing are called variables.