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Moseley's Law MCQ - Practice Questions with Answers
Edited By admin | Updated on Sep 25, 2023 25:23 PM | #NEET
Quick Facts
-
14 Questions around this concept.
Solve by difficulty
If the frequency of X−rays emitted from the element with atomic number 31 is
, then the frequency of
X−rays emitted from the element with atomic number 51 would be
The value of the wave length line of Silver (z=47).
(Given R= )
The $\mathrm{k}_{\alpha}$ radiation of $\mathrm{M}_0(\mathrm{z}=42)$ has a wavelength of $0.71 \dot{\mathrm{~A}}$, the wave length of the corresponding radiation of $\mathrm{Cu}(z=29)$
ray from a tube with a target
of atomic number
shows strong
lines for target
and weak
lines for impurities. The wavelength of
lines is
for target
for two impurities.
Screening constant of
lines is unity. Select the correct statement(s).
wavelength emitted by an atom of atomic number
is
. Find the atomic number for an atom that emits
radiation with wavelength
:
Characteristic X-rays of frequency are produced when transitions from K-shell take place in a certain target material. Use Mosley's law to determine the atomic number of the target material. Given Rydberg constant
Which element has a line of wavelength
?
An X-ray tube with a copper target is found to emit lines other than those due to copper. The line of copper is known to have a wavelength 1.5405 A0 and the other two
lines observed have wavelengths
and
. Identify the impurities (find the value of Z, atomic number).
Concepts Covered - 1
Moseley's Law
Moseley's Law-
During the time when the periodic table is arranged with atomic weight, Moseley measured the frequency of charcterstic X -rays from a large number of elements and plotted the square root of the frequency against its position number in the periodic table. He discovered that the plot is very close to a straight line. A portion of Moseley's plot is shown in figure where $\sqrt{\nu}$ of $\mathrm{K}_\alpha \mathrm{X}$-rays is plotted against the position number. From this linear relation, Moseley concluded that there must be a fundamental property of the atom which increases by regular steps as one moves from one element to the other. This quantity was later identified to be the number of protons in the nucleaus and was referred to as the atomic number.
The frequency $\nu$ of a characteristic X -ray of an element is related to its atomic number Z by
$$
\sqrt{\nu}=a(Z-b)
$$
where a and b are constants called proportionality and screening (or shielding) constants. For K series, $a=\sqrt{\frac{3 R c}{4}}$ and that of b is 1 . Here R is Rydberg's constant and c is speed of light (as in Bohr's model).
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