Structure of Atom - Result Question 22
####23. The spectrum of $He$ is expected to be similar to that
[1988]
(a) $H$
(b) $Li^{+}$
(c) $Na$
(d) $He^{+}$
Topic 3: Dual Behaviour of Matter and Heisenberg Uncertainty Principle
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Solution:
- (b) Both $He$ and $Li^{+}$contain 2 electrons each, therefore their spectrum will be similar.
24 .
(c) $n \lambda=2 \pi r$
$ \begin{aligned} \lambda & =\frac{2 \pi}{n} r \\ r_n & =a_0 n^{2} \\ r_2 & =52.9 \times(2)^{2} pm \\ \therefore \quad \lambda & =\frac{2 \pi}{2} \times 52.9 \times 4 \\ \lambda & =211.6 \pi pm \end{aligned} $
