MCQs of Atoms

Atoms MCQs

Showing 121 to 130 out of 146 Questions

121.

The shortest wavelength of X-rays emitted from an X-ray tube, operated at 2 × 10⁶ V is of the order of _____ .

(a)	1 Å
(b)	0.15 Å
(c)	10^-2 Å
(d)	10⁵ Å

122.

X-rays are produced in X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from _____ .

(a)	0 to ∞
(b)	λ_min to ∞, where λ_min > 0
(c)	0 to λ_max, where λ_max < ∞
(d)	λ_min to λ_max, where 0 < λ_min < λ_max < ∞

123.

The power of an X-ray tube is 16 W, if the potential difference applied across the tube is 5 kV, then the number of electrons striking the target per sec is _____ .

(a)	8.4 × 10¹⁶
(b)	5 × 10¹⁷
(c)	2 × 10¹⁶
(d)	2 × 10¹⁹

124.

X - ray from a tube with a target of atomic number Z shows strong K_{α} lines for target A and two weak K_{α} lines for impurities . The wavelength of K_{α} lines is λ_{0} for target A and λ_{1} and λ_{2} for two impurities respectively . \frac{λ_{0}}{λ_{1}} = 4 and \frac{λ_{0}}{λ_{2}} = \frac{1}{4} . The screening constant of K_{α} lines is unity . Select the correct alternatives (s)

_____ .

(a)	the atomic number of first impurity is 2Z - 1
(b)	the atomic number of first impurity is 2Z + 1
(c)	$the atomic number of second impurity is \frac{Z + 1}{2}$
(d)	$the atomic number of second impurity is \frac{Z}{2} + 1$

125.

When the voltage applied to an X-ray tube increases from V₁ = 10 kV to V₂ = 20 kV, the wavelength interval between K_α line and cut off wavelength of continuous spectrum increase by a factor of 3. Atomic number of the metallic,target is _____ .

(a)	28
(b)	29
(c)	65
(d)	66

126.

Which of the following is related with characteristic emission of X-rays ______.

(a)	α - particle emission
(b)	electron emission
(c)	positron emission
(d)	K - electron capturing

127.

In X-ray spectrum wave length of λ line K_α depends on atomic number Z as _____ .

(a)	$λ \propto Z^{2}$
(b)	$λ \propto {(Z - 1)}^{2}$
(c)	$λ \propto \frac{1}{(Z - 1)}$
(d)	$λ \propto \frac{1}{{(Z - 1)}^{2}}$

128.

If V be the accelerating voltage, then the maximum frequency of continuous X-rays is given by _____ .

(a)	$\frac{e h}{V}$
(b)	$\frac{h V}{e}$
(c)	$\frac{e V}{h}$
(d)	$\frac{h}{e V}$

129.

The wavelength of K_α X-rays produced by an X-ray tube is 0.76 Å. The atomic number of the anode material of the tube is _____ .

(a)	20
(b)	60
(c)	41
(d)	80

130.

The wavelength of the most energetic X-rays emitted when a metal target is bombarded by the electrons having kinetic energy 10 keV is approximately _____ .

(a)	1.24 Å
(b)	4 Å
(c)	0.31 Å
(d)	0.124 Å

Showing 121 to 130 out of 146 Questions