Answer:
6.73g
Explanation:
T½ = 5.2days
No = 80g
N = ?
T = 20.8days
We'll have to find the disintegration constant first so that we can plug it into the equation that will help us find the mass of the sample after 20.8 days
T½ = In2 / λ
T½ = half life
λ = disintegration constant
λ = In2 / T½
λ = 0.693 / 5.8
λ = 0.119
In(N / No) = -λt
N = final mass of the radioactive sample
No = initial mass of the sample
λ = disintegration constant
t = time for the radioactive decay
In(N/No) = -λt
N / No = e^-λt
N = No(e^-λt)
N = 80 × e^-(0.119 × 20.8)
N = 80 × e^-2.4752
N = 80 × 0.0841
N = 6.728g
The mass of the sample after 20.8 days is approximately 6.73g
Answer:
Different types of isotopes are used for different materials or objects. For radiometric dating, uranium-235 is considered best for it while carbon-14 is used for dating of rocks. It is also used for dating of wood samples.
Explanation:
Carbon-14 and uranium-235 are used for different materials or objects for measuring the age of these materials. These two isotopes are radioactive in nature which means they emit gamma radiations which allow us to find the age of different objects. Carbon-14 has a low half life so it can be used for those objects which are present before thousands of years while uranium-235 is used for materials which are millions of years old due to high half life.
Answer: The closeness of a measurement to its true value is a measure of its accuracy.
Explanation:
Precision refers to the closeness of two or more measurements to each other. Example: If we measure weight four times and we get 60 kg each time. Then the measurement is very precise.
Accuracy refers to the closeness of a measured value to a standard or known value. Example: If the weight of the body is 60 kg and one person measures 58 kg and another person measures 59 kg. Then, the weight measured by second person is more accurate.
Thus the closeness of a measurement to its true value is a measure of its accuracy
<h3>
Answer:</h3>
2 H₂ + O₂ → 2H₂O
<h3>
Explanation:</h3>
- The equation that shows the conservation of atoms is the balanced one.
- In this case, the balanced equation is;
2 H₂ + O₂ → 2H₂O
Because it has 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.
- Chemical equations are balanced to obey the law of conservation of mass that requires the mass of the reactant to be equal to the mass of the products.
- Balancing chemical equations makes the number of atoms of each element in the equation equal, thus conserving the mass in the chemical reactions.
