D. because matter is uniform through and cannot be separated into other substances by physical means.
For radioactive decay, we can relate current amount, initial amount, decay constant and time using:
N = No x exp(-λt)
Half-life = ln(2)/λ
λ = ln(2) / 5730
N/No = 80% = 0.8
0.8 = exp( -ln(2)/5730 x t)
t = 1844 years
That would be phosphorus. It’s electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^3
Tropical or warm air masses form in the tropics and have low air pressure.
polar or cold air masses form north of 50 degrees north latitude and south of 50 degrees south latitude
Can’t have anything in Detroit
