Answer:
The answer to the question is
50 % of the original amount of potassium 40 will be left after one half life or 1.25 billion years
Explanation:
To solve the question we note that the half life is the time for half of the quantity of substance that undergoes radioactive decay to disintegrate, thus
we have
half life of potassium 40 K₄₀ = 1.25 billion years
To support the believe tht the rock was formed 1.25 billion years ago we have

After 1.25 billion years we have
=
=0.5 of
will be left or 50 % of the original amount of potassium 40 will be left
The term "solution" is more frequently used when a homogeneous mixture<span> is a liquid, although it is sometimes used if the </span>homogeneous mixture<span> is a gas.</span>
Answer:
The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).
Explanation:
The charge that 3 protons, 3 neutrons and 2 electrons have is that it will be a cation of Li with a charge of +1.
Li^+1.
A) Metal has luster
Metals are ductile, malleable, and good conductors of heat.