What were the gases of the earth when it was born?

When the Earth was formed about 4.5 billion years ago, it primarily consisted of gases such as hydrogen and helium, which were abundant in the early solar nebula. As the planet cooled, volcanic activity released water vapor, carbon dioxide, ammonia, and methane, contributing to the early atmosphere. This primordial atmosphere was vastly different from today's, lacking oxygen and being more conducive to the development of life as we know it. Over time, photosynthetic organisms contributed to the gradual increase of oxygen in the atmosphere.