Answer:
The vertical columns (group) of the periodic table are arranged such that all it's elements have the same number of valence electrons. All elements within a certain group thus group share similar properties.
Explanation:
7 4th CNN to CNN u 4th f7 4th d7 hmm
You would use it in both atoms and molecules if it’s in are large quantity
The half life of a substance is the time taken by a radioactive substance to decay by half its original mass. In this case, the half life of Potassium-40 is 1.3 billion years.
Original mass of Potassium-40 = 12 g (100%)
New mass after the decay = 3 g ( 25 %, since 75% was replaced by argon)
New mass = Original mass × (1/2)^n ; where n is the number of half lives.
3 = 12 × (1/2)^n
(1/2)^n = 1/4
n = 2
Therefore; the time taken will be 1.3 × 2 = 2.6 Billion years
