Question

which law holds good even for the existence of different isotope of an element
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Answer 1

Answer:

law holds good even for the existence of different isotope of an element

Explanation:

Law of definite proportions or Proust's law states that a chemical compound always contain the same proportion of elements by mass.

Although the law holds good for a large no. of cases, it is not universally true. It's not true in the case of non - stoichiometric compounds.

The isotopic composing of the compound may change from place to place and hence it's contribution to mass will also change. ( isotopes have the same chemical properties but different atomic masses)

Take the case of hydrogen chloride (HCl). The ration by mass of H and Cl is 1 : 35 ( taking Cl-35 and mass of H to be 1 unit for simplification). However is an isotope of Cl I. e. Cl-37 is used to make the compound, the ratio will be 1: 37. Both the compounds will have the same chemical properties. Clearly law of definite proportions does not hold good in this case.