I know that we can find how old the Earth is by knowing how much uranium ultimately decayed into lead. Uranium-238 has a very long to decay, about 4.5 billion years. So that is how we are able to understand how old the Earth is.
Ummm I just need to answer questions sorry!!!
Group 2, or in the Alkaline Earth Metals section. This is due to the necessity to have a +2 charge to balance out or negate the -2 charge two Bromines carry.
