The most abundant element in the Sun and in the stars are hydrogen and helium. Like most of the stars, there is a spontaneous radioactive reaction happening in the Sun. Hydrogen is transformed into Helium. As long as the stars are young, the most abundant element is hydrogen.
Answer:
6.25 g
Explanation:
From the question given above, the following data were obtained:
Half-life (t½) = 68.8 years
Time (t) = 344 years
Original amount (N₀) = 200 g
Amount remaining (N) =?
Next, we shall determine the number of half-lives that has elapsed. This can be obtained as follow:
Half-life (t½) = 68.8 years
Time (t) = 344 years
Number of half-lives (n) =
n = t / t½
n = 344 / 68.8
n = 5
Thus, 5 half-lives has elapsed.
Finally, we shall determine the amount of the Uranium-232 that remains. This can be obtained as follow:
Original amount (N₀) = 200 g
Number of half-lives (n) = 5
Amount remaining (N) =?
N = 1/2ⁿ × N₀
N = 1/2⁵ × 200
N = 1/32 × 200
N = 200 / 32
N = 6.25 g
Thus, the amount of Uranium-232 that remains is 6.25 g
Answer:
5:22 am
Explanation:
The gas X decays following a first-order reaction.
The half-life (
) is 25 min. We can find the rate constant (k) using the following expression.
![k = \frac{ln2}{t_{1/2}} =\frac{ln2}{25min} = 0.028 min^{-1}](https://tex.z-dn.net/?f=k%20%3D%20%5Cfrac%7Bln2%7D%7Bt_%7B1%2F2%7D%7D%20%3D%5Cfrac%7Bln2%7D%7B25min%7D%20%3D%200.028%20min%5E%7B-1%7D)
We can find the concentration of X at a certain time (
) using the following expression.
![[X] = [X]_0 \times e^{-k \times t}](https://tex.z-dn.net/?f=%5BX%5D%20%3D%20%5BX%5D_0%20%5Ctimes%20e%5E%7B-k%20%5Ctimes%20t%7D)
where,
: initial concentration of X
t: time elapsed
![\frac{[X]}{[X]_0}= e^{-k \times t}\\\frac{1/10[X]_0}{[X]_0}= e^{-0.028min^{-1} \times t}\\t=82min](https://tex.z-dn.net/?f=%5Cfrac%7B%5BX%5D%7D%7B%5BX%5D_0%7D%3D%20e%5E%7B-k%20%20%5Ctimes%20t%7D%5C%5C%5Cfrac%7B1%2F10%5BX%5D_0%7D%7B%5BX%5D_0%7D%3D%20e%5E%7B-0.028min%5E%7B-1%7D%20%20%5Ctimes%20t%7D%5C%5Ct%3D82min)
The earliest time Professor Utonium can come back to do experiments in the lab is:
4:00 + 82 = 5:22 am
Answer:
Food has to be digested into smaller component nutrients that are then absorbed and used throughout your body. Calories in food provide your body with the energy it needs to complete vital processes such as cellular maintenance and reproduction, and respiration.
Explanation:
can i have a brainlist :)
Answer:
8.59
⋅
10
17
Explanation:
You can start by figuring out the energy of a single photon of wavelength
505 nm
=
505
⋅
10
−
9
m
.
To do that, use the equation
E
=
h
⋅
c
λ
Here
h
is Planck's constant, equal to
6.626
⋅
10
−
34
.
J s
c
is the speed of light in a vacuum, usually given as
3
⋅
10
8
.
m s
−
1
λ
is the wavelength of the photon, expressed in meters
Plug in your value to find--notice that the wavelength of the photon must be expressed in meters in order for it to work here.
E
=
6.626
⋅
10
−
34
J
s
⋅
3
⋅
10
8
m
s
−
1
505
⋅
10
−
9
m
E
=
3.936
⋅
10
−
19
J
So, you know that one photon of this wavelength has an energy of
3.936
⋅
10
−
19
J
and that your laser pulse produces a total of
0.338 J
of energy, so all that you need to do now is to find how many photons are needed to get the energy output given to you.
0.338
J
⋅
1 photon
3.936
⋅
10
−
19
J
=
8.59
⋅
10
17
photons
−−−−−−−−−−−−−−−−−
The answer is rounded to three sig figs.