Answer:
13.5 years
Explanation:
Initial Concentration [Ao] = 10g
Final Concentration [A] = 0.768g
Time t= 50 years
Half life t1/2 = ?
These quantities are related by the following equations;
ln[A] = ln[Ao] - kt ......(i)
t1/2 = ln(2) / k ...........(ii)
where k = rate constant
Inserting the values in eqn (i) and solving for k, we have;
ln(0.768) = ln(10) - k (50)
-0.2640 = 2.3026 - 50k
50k = 2.3026 + 0.2640
k = 2.5666 / 50 = 0.051332
Insert the value of k in eqn (ii);
t1/2 = ln(2) / k
t1/2 = 0.693 / 0.051332 = 13.5 years
<span>The correct
answer between all the choices given is the 4th choice or letter D. I am
hoping that this answer has satisfied your query and it will be able to help
you in your endeavor, and if you would like, feel free to ask another question.</span>
The molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.
<h3>How to calculate molar mass?</h3>
The molar mass of a substance can be calculated by dividing the mass of the substance by its number of moles.
However, the number of moles of the gas in this question needs to be calculated first using the ideal gas law equation:
PV = nRT
Where;
- P = pressure
- V = volume
- n = number of moles
- T = temperature
- R = gas law constant
1.04 × 0.854 = n × 0.0821 × 302
0.888 = 24.79n
n = 0.888/24.79
n = 0.036mol
Molar mass of gas = 3.82g/0.036mol
Molar mass = 106.66g/mol
Therefore, the molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.
Learn more about molar mass at: brainly.com/question/12127540
The seashell is <u>28747.96 years old.</u>
<u />
Why?
If we need to calculate how old is something, we can use the equation for radioactive decay rate. It's possible using the C-14 half-life (5740 years) as reference. Remember, C-14 is used because all the living things take up the element from the atmosphere, when an organism dies, the amount of carbon starts to decay (very slowly).
Decay rate half life:
Where,
is the initial number of atoms (undecayed)
is the the number of atoms at time (undecayed)
is the decay rate
Now, isolating the decay rate of the formula, we have:
{
Also, we can get the value of the decay rate (half life), using the following formula:
Then, using the given information, we have:
Hence, the seashell is 28748.96 years old.
Have a nice day!
