MCQs of Atoms

Atoms MCQs

Showing 91 to 100 out of 146 Questions

91.

The electron in a hydrogen atom jumps from ground state to a higher energy state where its velocity is reduced to one-third its initial value. If the radius of the orbit in the ground state is r, the radius of the new orbit will be _____ .

(a)	3 r
(b)	9 r
(c)	$\frac{r}{3}$
(d)	$\frac{r}{9}$

92.

Choose the correct relation from the following for the hydrogen like atoms _____.

(a)	$r_{n} = n^{2} r_{1}, E_{n} = \frac{E_{1}}{n^{2}}, v_{n} = \frac{v_{1}}{n}$
(b)	$r_{n} = \frac{r_{1}}{n^{2}}, E_{n} = n^{2} E_{1}, v_{n} = \frac{v_{1}}{n}$
(c)	$r_{n} = \frac{r^{2}}{n^{2}}, E_{n} = \frac{E_{1}}{n^{2}}, v_{n} = \frac{v_{1}}{n^{2}}$
(d)	$r_{n} = n^{2} r, E_{n} = n^{2} E_{1}, v_{n} = n^{2} v_{1}$

93.

The quantum number corresponding to orbit of diameter 918 Å in hydrogen atom will be approximately be _____.

(a)	39
(b)	31
(c)	9
(d)	30

94.

The binding energy of an electron at n = ∞ in doubly ionized Lithium atom will be _____ .

(a)	zero
(b)	-3.6 eV
(c)	27.2 eV
(d)	∞

95.

According to Bohr's theory, only those orbits of electrons are stable for which the orbital angular momentum is _____.

(a)	$\frac{n}{h}$
(b)	$n h$
(c)	$\frac{h}{n}$
(d)	None of the above

96.

The velocity of electron in an atom according to Bohr's theory is _____ .

(a)	$\frac{n h}{2 π mr}$
(b)	$\frac{1}{2 π mr}$
(c)	$2 π mr$
(d)	None of the above

97.

The radius (r_n) of circular orbits is _____ .

(a)	∝ n
(b)	$\propto \frac{1}{n^{2}}$
(c)	∝ n²
(d)	$1 \propto \frac{1}{n}$

98.

The limit of Balmer series is 3646 Å. The wavelength of the first member of this series will be ______.

(a)	1000 Å
(b)	3646 Å
(c)	7200 Å
(d)	6563 Å

99.

The ratio of speed of electron in the ground state of hydrogen atom to that of light is _____.

(a)	$\frac{2}{237}$
(b)	$\frac{1}{2}$
(c)	$\frac{1}{137}$
(d)	$\frac{1}{237}$

100.

The angular momentum of an electron is J. Its magnetic moment will be _____ .

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

Showing 91 to 100 out of 146 Questions