Answer:
Radio astronomy began in 1933 when an engineer named Karl Jansky accidentally discovered that radio waves come not just from inventions we create but also from natural stuff in space.
Cinder cone volcanoes can be associated with either constructive or destructive margins.<span>
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Answer:
(a) ![[Y_{p} ]_{max} = \frac{2f}{1+f}](https://tex.z-dn.net/?f=%5BY_%7Bp%7D%20%5D_%7Bmax%7D%20%3D%20%5Cfrac%7B2f%7D%7B1%2Bf%7D)
(b)
;
= 0.026
Explanation:
Since the neutron-to-proton ratio at the time of nucleosynthesis is given:

Therefore:

Then, to determine the maximum ⁴He fraction if all the available
neutrons bind to all the protons. Since, there are 2 protons and 2 neutrons in a ⁴He nucleus, it shows that there would be
nuclei of ⁴He.
In addition, a ⁴He nucleus has a mass of
, where
is the mass of one proton. Thus,
nuclei of such nuclei will have a mass of
*
.
Assuming that
, there would be a total of
protons and neutrons with a total mass of
.
Thus:![[Y_{p} ]_{max} = \frac{2f}{1+f}](https://tex.z-dn.net/?f=%5BY_%7Bp%7D%20%5D_%7Bmax%7D%20%3D%20%5Cfrac%7B2f%7D%7B1%2Bf%7D)
(b) Given:
; τ
= 3*60s = 180 s
![f_{new} = \frac{n_{nf} }{n_{pf} } = \frac{exp (-200/180)}{5 +[1- exp(-200/180)]} =\frac{0.077}{5.923} = 0.013](https://tex.z-dn.net/?f=f_%7Bnew%7D%20%3D%20%5Cfrac%7Bn_%7Bnf%7D%20%7D%7Bn_%7Bpf%7D%20%7D%20%3D%20%5Cfrac%7Bexp%20%28-200%2F180%29%7D%7B5%20%2B%5B1-%20exp%28-200%2F180%29%5D%7D%20%3D%5Cfrac%7B0.077%7D%7B5.923%7D%20%3D%200.013)
= (2*0.013)/(1+0.013) = 0.026
Answer:
There are so many questions which one you don't know