Final answer:
The gases collected over water are found using the option c)water displacement method, where gas produced in a reaction displaces water in an inverted bottle, allowing for the collection and measurement of the gas mixed with water vapor.
Step-by-step explanation:
To find the gases collected over water, you would use C) the water displacement method.
This technique involves a bottle filled with water and turned upside down in a water-filled pan. As gas is produced in a reaction flask, it is channeled through rubber tubing under the water bottle, displacing the water and filling the bottle with the gas. The gas is mixed with water vapor, and you can correct for the contribution of water vapor to get the true value of the gas pressure using Dalton's Law, which accounts for the vapor pressure of water at a given temperature.