MCQs of Atoms

Atoms MCQs

Showing 131 to 140 out of 146 Questions

131.

What is the approximate ratio of wavelength of radiations K_α1 and K_α2 when atomic number of first target is Z₁ = 65 and atomic number of second target is Z₂ = 81 ?

(a)	$\frac{1}{4}$
(b)	$\frac{1}{16}$
(c)	$\frac{2}{\sqrt{5}}$
(d)	$\frac{25}{16}$

132.

The angular momentum of an electron of Na-atom in n = 4 orbit is _____ Js.

(a)	13.25 × 10^-34
(b)	16.58 × 10^-34
(c)	4.22 × 10^-34
(d)	5.27 × 10^-34

133.

If the potential energy of the electron in the Hydrogen atom is

\frac{- e^{2}}{4 {πε}_{0} r}

, then what is its kinetic energy ?

(a)	$\frac{- e^{2}}{8 {πε}_{0} r}$
(b)	$\frac{- e^{2}}{4 {πε}_{0} r}$
(c)	$\frac{e^{2}}{8 {πε}_{0} r}$
(d)	$\frac{- e^{2}}{4 {πε}_{0} r}$

134.

In Moseley's Experiment the nature of graph

\sqrt{f} \to Z

is _____.

(a)	Circle
(b)	Elliptical
(c)	Parabolic
(d)	Straight line

135.

The minimum wavelength of X-rays produced by electrons accelerated through a potential difference of V volt is directly proportional to _____ .

(a)	$V^{\frac{1}{2}}$
(b)	$V^{2}$
(c)	$V^{- \frac{1}{2}}$
(d)	V^-1

136.

What will be the angular momentum in fourth orbit, if L is the angular momentum of the electron in the second orbit of hydrogen atom ?

(a)	$\frac{2}{3} L$
(b)	$\frac{L}{2}$
(c)	2L
(d)	$\frac{3}{2} L$

137.

The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. The number of electrons striking the target per second is _____.(e = 1.6 × 10^-19 C)

(a)	2 × 10¹⁶
(b)	4 × 10¹⁶
(c)	2 × 10^-6
(d)	1.6 × 10⁶

138.

According to the Bohr's atomic model, the relation between principal quantum number (n) and radius of orbit (r) is _____ .

(a)	$r \propto n^{2}$
(b)	$r \propto \frac{1}{n^{2}}$
(c)	$r \propto \frac{1}{n}$
(d)	$r \propto n$

139.

The ratio of magnetic dipole moment to that of angular momentum of electron of mass m and charge e in Bohr's orbit of hydrogen atom is _____.

(a)	$\frac{e}{2 m}$
(b)	$\frac{e}{m}$
(c)	$\frac{2 m}{e}$
(d)	$\frac{m}{e}$

140.

The distance of the closest approach of an alpha particle fired at a nucleus with kinetic energy K is r₀. The distance of the closest approach, when the α-particle is fired at the same nucleus with kinetic energy 2 K will be _____.

(a)	$\frac{r_{0}}{2}$
(b)	$\frac{r_{0}}{4}$
(c)	4r₀
(d)	2r₀

Showing 131 to 140 out of 146 Questions