Answer:
= 72900 years
Explanation:
- The half-life is the time taken by a radioactive material to decay by half the original amount.
- The half-life of plutonium-239 is 24300 years which means it takes 24300 years to decay by half the original amount.
To calculate the time taken for a mass of 8 kg to decay to 1 kg we use;
New mass = Original mass x (1/2) ^n, where n is the number of half-lives
Therefore;
1 kg = 8 kg × (1/2)^n
1/8 = (1/2)^n
solving for n;
n =3
Therefore;
Time = 3 × 24300 years
= 72900 years
It will, therefore, take 72900 years for 8 kg of plutonium-239 to decay to 1 kg.
Answer:
The pressure will be 0.4 atm.
Explanation:
The gas laws are a set of chemical and physical laws that allow determining the behavior of gases in a closed system. The parameters evaluated in these laws are pressure, volume, temperature and moles.
As the volume increases, the gas particles (atoms or molecules) take longer to reach the walls of the container and therefore collide with them less times per unit of time. This means that the pressure will be lower because it represents the frequency of collisions of the gas against the walls. In this way pressure and volume are related, determining Boyle's law which says:
"The volume occupied by a certain gaseous mass at constant temperature is inversely proportional to pressure"
Boyle's law is expressed mathematically as:
P*V= k
If you initially have the gas at a volume V1 and press P1, when the conditions change to a volume V2 and pressure P2, the following is satisfied:
P1*V1= P2*V2
In this case:
- P1= 1.2 atm
- V1= 4 L
- P2= ?
- V2= 12 L
Replacing:
1.2 atm* 4 L= P2* 12 L
Solving:

P2= 0.4 atm
<u><em>The pressure will be 0.4 atm.</em></u>
Answer:
mass number = 18
Explanation:
The mass number is the total amount of protons and neutrons in an atom. Therefore, if there are 8 protons and 10 neutrons, the mass number is 18 (8 + 10 = 18).
They represent elements by using symbols