The amount left after 20 years = 154.15 mg
<h3>Further explanation
</h3>
The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually radioactive elements have an unstable atomic nucleus.
The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles
The decay formula for isotope :
Then for t=20 years, the amount left :
The decreasing order of wavelengths of the photons emitted or absorbed by the H atom is : b → c → a → d
Rydberg's formula :
,
where λ is the wavelength of the photon emitted or absorbed from an H atom electron transition from to and = 109677 is the Rydberg Constant. Here and represents the transitions.
(a) =2 to = infinity
= 109677/4 [since 1/infinity = 0] Therefore, = 4 / 109677 = 0.00003647 m
(b) =4 to = 20
= 6580.62
Therefore, = 1 / 6580.62 = 0.000152 m
(c) =3 to = 10
= 11089.56
Therefore, = 1 / 11089.56 = 0.00009 m
(d) =2 to = 1
= - 82257.75
Therefore, = 1 /82257.75 = - 0.0000121 m
[Even though there is a negative sign, the magnitude is only considered because the sign denotes that energy is emitted.]
So the decreasing order of wavelength of the photon absorbed or emitted is b → c → a → d.
Learn more about the Rydberg's formula athttps://brainly.com/question/14649374
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One way of expressing concentration is by percent. It may be on the basis of mass, mole or volume. Percent is expressed as the amount of solute per amount of the solution. For this case, we are given the percent by mass. In order to solve the amount of solute, we multiply the percent with the amount of the solution.
Mass of solute = percent by mass x mass solution
Mass of solute = 0.0350 x 2.50 x10^2 = 8.75 grams of solute
D. All of the above. Developing medicine, analyzing compounds and producing new product such as plastic all have to deal with chemistry.
Answer:
12
Explanation:
There are 4 sulfur atoms in SO4
4×3=12
This means that it turns into 3×(SO4)
=3SO4