Modern Physics Ques 28
- If the atom ${ } _{100} Fm^{257}$ follows the Bohr’s model and the radius of last orbit of ${ } _{100} Fm^{257}$ is $n$ times the Bohr radius, then find $n$
$(2003,2 M)$
(a) $100$
(b) $200$
(c) $4$
(d) $1 / 4$
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Answer:
Correct Answer: 28.(d)
Solution:
Formula:
Radius And Speed Of Electron In Hydrogen Like Atoms:
- $\quad\left(r _m\right)=(\frac{m^{2}}{z})(0.53 \AA)=(n \times 0.53) \AA$
$ \therefore \quad \frac{m^{2}}{z}=n $
$m=5$ for ${ } _{100} Fm^{257}$ (the outermost shell) and $z=100$
$ \therefore \quad n=\frac{(5)^{2}}{100}=\frac{1}{4} $
BETA
