When an electron in an excited Mo atom falls from L to K, shell, an X-ray is emitted. These X-ray are diffracted at angle of 7.75 by planes with a separation of 2.64 Å. What is the difference in energy between K-shell and L-shell in Mo assuming a first order diffraction (sin 7.75 = 0.1349)?


Correct option is

27.88 × 10–16 J


Bragg’s equation




                    = 0.7123 × 10–10 m

Also, we know that



                    = 27.88 × 10–16 J.



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Match box belongs to


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A compound CuCl has fcc structure. Its density is 3.4 g cm–3, what is the length of unit cell?


A metal crystallizes into two cubic phases fcc and bcc whose unit cell lengths are 3.5 and 3.0 Å respectively. What is the ratio of densities of fcc and bcc?


The radius of a divalent cation M2+ is 94 pm and that of divalent anion X2–is 146 pm. Thus, M2+ X2– has