Grade 12 Physics - Atoms Quiz (Set 2)

Question 1

What did the Rutherford alpha-particle scattering experiment primarily reveal about atomic structure?

Accepted Answer

B) Positively charged nucleus occupies a tiny volume compared to the whole atom.

Answer

A) Electrons are concentrated in the center of the atom.

Answer

C) Neutrons orbit the nucleus in fixed energy levels.

Answer

D) Mass of an atom is uniformly distributed throughout its entire volume.

Question 2

In Bohr's atomic model of the hydrogen atom, which physical quantity is quantized?

Accepted Answer

B) Angular momentum of the electron

Answer

A) Linear momentum of the electron

Answer

C) Work function of the atom

Answer

D) Total charge of the nucleus

Question 3

According to Bohr's quantization condition, the angular momentum $L$ of an electron in the $n$-th orbit is:

Accepted Answer

A) $L = \frac{nh}{2\pi}$

Answer

B) $L = \frac{2\pi h}{n}$

Answer

C) $L = \frac{n^2 h}{2\pi}$

Answer

D) $L = \frac{nh}{\pi}$

Question 4

How does the radius $r_n$ of the $n$-th Bohr orbit in a hydrogen atom scale with the principal quantum number $n$?

Accepted Answer

B) $r_n \propto n^2$

Answer

A) $r_n \propto n$

Answer

C) $r_n \propto \frac{1}{n}$

Answer

D) $r_n \propto \frac{1}{n^2}$

Question 5

If the ground state radius ($n=1$) of a hydrogen atom is $r_1 = 0.53 ext{ \AA}$, what is the radius of the second orbit ($n=2$)?

Accepted Answer

C) 2.12 \AA

Answer

A) 1.06 \AA

Answer

B) 1.59 \AA

Answer

D) 4.24 \AA

Question 6

What is the ratio of the speed of an electron in the first Bohr orbit ($n=1$) to its speed in the third orbit ($n=3$) of a hydrogen atom?

Accepted Answer

B) $3 : 1$

Answer

A) $1 : 3$

Answer

C) $1 : 9$

Answer

D) $9 : 1$

Question 7

What is the total energy of an electron in the ground state ($n=1$) of a hydrogen atom?

Accepted Answer

A) -13.6 eV

Answer

B) -3.4 eV

Answer

C) +13.6 eV

Answer

D) -1.51 eV

Question 8

If the total energy of an electron in a hydrogen orbit is -3.4 eV, what is its kinetic energy in that same orbit?

Accepted Answer

B) +3.4 eV

Answer

A) -3.4 eV

Answer

C) +6.8 eV

Answer

D) -6.8 eV

Question 9

What is the potential energy of an electron in the ground state ($n=1$) of a hydrogen atom where total energy is -13.6 eV?

Accepted Answer

C) -27.2 eV

Answer

A) -13.6 eV

Answer

B) +13.6 eV

Answer

D) +27.2 eV

Question 10

Which spectral series of the hydrogen atom lies entirely in the ultraviolet region?

Accepted Answer

C) Lyman series

Answer

A) Balmer series

Answer

B) Paschen series

Answer

D) Brackett series

Question 11

Which spectral series of the hydrogen atom falls in the visible light spectrum?

Accepted Answer

B) Balmer series

Answer

A) Lyman series

Answer

C) Paschen series

Answer

D) Pfund series

Question 12

According to de Broglie's hypothesis, a stable circular orbit of radius $r$ is formed when the orbit circumference $2\pi r$ is equal to:

Accepted Answer

B) An integral number of de Broglie wavelengths $n\lambda$

Answer

A) A half-integral number of wavelengths $\frac{n\lambda}{2}$

Answer

C) The square of the de Broglie wavelength $\lambda^2$

Answer

D) The inverse of the de Broglie wavelength $\frac{1}{\lambda}$

Question 13

What is the minimum ionization energy required to completely remove an electron from the ground state of a hydrogen atom?

Accepted Answer

C) 13.6 eV

Answer

A) 3.4 eV

Answer

B) 10.2 eV

Answer

D) 27.2 eV

Question 14

In an $\alpha$-particle scattering experiment, as the impact parameter $b$ approaches zero, the scattering angle $ heta$ approaches:

Accepted Answer

D) $180^\circ$

Answer

A) $0^\circ$

Answer

B) $45^\circ$

Answer

C) $90^\circ$

Question 15

The ground state energy of hydrogen is -13.6 eV. What is the energy of an electron in its first excited state ($n=2$)?

Accepted Answer

B) -3.4 eV

Answer

A) -6.8 eV

Answer

C) -1.51 eV

Answer

D) -0.85 eV

Question 16

Calculate the energy of the photon emitted when an electron in hydrogen transitions from level $n=3$ ($E_3 = -1.51 ext{ eV}$) to level $n=2$ ($E_2 = -3.40 ext{ eV}$).

Accepted Answer

A) 1.89 eV

Answer

B) 4.91 eV

Answer

C) 12.09 eV

Answer

D) 0.85 eV

Question 17

What is the ratio of kinetic energy $K$ to total energy $E$ of an electron in any Bohr orbit of a hydrogen atom?

Accepted Answer

B) $-1 : 1$

Answer

A) $1 : 1$

Answer

C) $2 : 1$

Answer

D) $-2 : 1$

Question 18

What is the shortest wavelength limit (series limit) for the Lyman series, expressed in terms of the Rydberg constant $R$?

Accepted Answer

A) $\frac{1}{R}$

Answer

B) $\frac{4}{R}$

Answer

C) $\frac{9}{R}$

Answer

D) $\frac{R}{4}$

Question 19

If electrons in a sample of hydrogen gas are excited to level $n=4$, what is the maximum number of spectral lines that can be emitted upon de-excitation?

Accepted Answer

C) 6

Answer

A) 3

Answer

B) 4

Answer

D) 10

Question 20

How does Rutherford's distance of closest approach $r_0$ for an $\alpha$-particle depend on its initial kinetic energy $K$?

Accepted Answer

B) $r_0 \propto \frac{1}{K}$

Answer

A) $r_0 \propto K$

Answer

C) $r_0 \propto \sqrt{K}$

Answer

D) $r_0 \propto \frac{1}{K^2}$