What elements would you measure the abundance of,if you wanted to infer the amount of normal ("baryonic")matter in the early universe?

Question

Quizplus · Accepted Answer

To infer the amount of normal ("baryonic") matter in the early universe, the best choice would be measuring the abundance of lithium and deuterium. This is because the abundance of lithium and deuterium in the early universe is directly related to the density of baryonic matter. Hydrogen and helium are the most abundant elements in the universe, and their abundance is not sensitive to the baryonic matter density. Carbon and oxygen are produced in stars and their abundance depends on complex processes, so they are not good indicators of the early universe.

What Elements Would You Measure the Abundance Of,if You Wanted