The amount left after 20 years = 154.15 mg
<h3>Further explanation
</h3>
The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually radioactive elements have an unstable atomic nucleus.
The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles
The decay formula for isotope :
Then for t=20 years, the amount left :
Answer:
C) It has a constant average kinetic energy
Explanation:
The average kinetic energy of the particles in a gas is directly proportional to the temperature of the gas, according to the equation.
k is the Boltzmann's constant
T is the absolute temperature of the gas
Therefore, temperature of a gas is a measure of the average kinetic energy of the particles.
In this problem, we are told that the gas is at constant temperature (and volume): therefore, according to the previous equation, this means that the average kinetic energy is also constant.
Dmitri Mendeleev
<span> Dmitri Mendeleev and Lothar Meyer individually came up with their own periodic law "when the elements are arranged in order of increasing atomic mass,
certain sets of properties recur periodically.</span>
3 mass number- proton number
