Q. Which of the following is/are correct for law of constant proportion?

1. It was given and stated by Lavoisier.
2. In a chemical substance the elements are always present in definite proportions by mass.

Select the correct answer from the codes given below:
Answer: Only 2
Notes: Lavoisier, along with other scientists, noted that many compounds were composed of two or more elements and each such compound had the same elements in the same proportions, irrespective of where the compound came from or who prepared it. This law was stated by Proust as "In a chemical substance the elements are always present in definite proportions by mass".