1. Which of the following choices demonstrates the law of constant composition? (Slides 2 ‒ 3: Laws on Matter) (a) Nitrogen and oxygen are both found in nature as diatomic molecules. (b) When 20.0 g of nitrogen and 32.0 g of oxygen are combined and allowed to react in two separate experiments, both times the product isolated from reaction contains 14.0 g of nitrogen and 32.0 g of oxygen. (c) Nitrogen and oxygen gases are mixed to produce a sample consisting of 20.0 g of nitrogen and 32.0 g of oxygen. (d) When 14.0 g of nitrogen and 32.0 g of oxygen are mixed and react, there is no measurable change in mass during the reaction. (e) Nitrogen and oxygen are gases found in air, nitrogen is approximately 79% of air and oxygen is approximately 21%.