Someone plz help me with this question

Several billion years ago which gas was the least prevailant in the atmosphere

Which of the following is a true statements about viruses? viruses have no nucleus. viruses are alive. viruses have a cell membrane. all viruses are deadly.

The starting materials in a nuclear change have a total mass of 2.3465 x 10-27 kg. after the change, the resulting materials have a mass of 2.3148 x 10-27 kg. how much energy was released during the change? 2.85 x 10-12 2.08 * 10-10 j 0 211 * 10-10 j 8.56 * 10-43