Answer:
Because it keeps track of all the elements
Water is a polar solvent. Since, 'Like dissolves like' a polar compound will be most soluble in water whereas a non-polar compound will be the least soluble.
The increasing order of polarity for the given organic compounds is:-
CH3OCH3 < CH3NH2 < CH3CHO < CH3CH2OH
Ether is the least polar and hence least soluble in water.
MgCl2 because it is the only option in which a metal appears with a nonmetal. In this case, the metal transfers electrons to the nonmental because the metal has a lower ionization energy.
Rotting vegetables is a chemical change I think.
