We know this because of the discovery of fossils and bones. We can find out roughly when they existed because of carbon dating.
Answer:
CuSO4(aq)
Explanation:
The aqueous for of CuSO₄ is an electrolyte and it will conduct electricity.
CuSO₄ is an ionic substance and in solid state, it will not have the ability to conduct electricity.
- In aqueous form, it will contain free mobile ions which serves as carriers of electric current.
- In the solid state, the ions are arranged into a crystal lattice and will not conduct a current of electricity.
- The remaining given compounds will not conduct electricity as they are non-polar and do not have free mobile electrons.
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
