Explanation
The angular momentum of α particles is conserved because there is no external torque.
Hint:
Number of Photons emitted by H-atom if it is excited to nth excited state is,
photons=n(n−1)2
Step 1: Calculate the number of photons emitted by H-atom
Hydrogen atom is excited to 4th excited state, so number of photons emitted by using formula is,
⇒photons=4(4−1)2
⇒photons=6
Thus, 6 photons are emitted if the Hydrogen atom is excited to 4th excited state.
Option B is correct.
For an atom of atomic number Z, The radius of nth orbit is given as,
rn=n2aoZ
Where, ao is Bohr’s radius, ao=53pm
Correct Option : Option D.
Explanation for correct answer:
a) 11H
Z=1
For shortest orbit, n=1
Therefore, r1=12×531=53pm
b) 12H
c) He+
Z=2
Therefore, r1=12×532=26.5pm
d) Li+
Z=3
Therefore, r1=12×533=17.667pm
The radius of shortest orbit of Li+ is closest to 18pm. Thus Option D is the correct answer.
The ratio of momenta of an electron and a \alpha -particle which is accelerated from rest by a potential difference of 100 V is:
Hint: The Rutherford alpha particle scattering experiment showed that most of the space of the atom is empty
Explanation: The Rutherford alpha particle scattering experiment has the following observation: 1. Most of the alpha particle remains undeflected that means most of the space was empty and the particles came undeflected by positive charges in the atom. It was a very small portion and termed as the nucleus.
2. Some of the alpha particles show a small deviation from the original path.
3. Very few particles bounced backSo, Conclusions can be made from this as;
1. Most of the space in the atom remains empty.
2. And a large amount of mass is concentrated in the small space called a nucleus.
Final answer: The correct answer is C.
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