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12.Atoms
normal
The wavelengths of ${K_\alpha }$ $X-$ rays of two metals $'A'$ and $'B'$ $\frac{4}{{1875R}}$ and $\frac{1}{{675R}}$ respectively, where $'R'$ is Rydberg's constant. The number of elements lying between $'A'$ and $'B'$ according to their atomic numbers is
A
$3$
B
$6$
C
$5$
D
$4$
Solution
$\frac{1}{{{\lambda _{{{\rm{k}}_\alpha }}}}} = \frac{{3{\rm{R}}}}{4}{({\rm{Z}} – 1)^2}$
Standard 12
Physics
Similar Questions
Match List $- I$ (Experiment performed) with List $-II$ (Phenomena discovered/associated) and select the correct option from the options given the lists
| List $- I$ | List $- II$ |
| $(1)$ Davisson and Genner | $(i)$ Wave nature of electrons |
| $(2)$ Millikan's oil drop experiment | $(ii)$ Charge of an electron |
| $(3)$ Rutherford experiment | $(iii)$ Quantisation of energy levels |
| $(4)$ Franck-Hertz experiment | $(iv)$ Existence of nucleus |
