Atomic Structure Examples of Multiple Choice Questions

1.

Which of the following has a positive charge?

(a) proton

(b) neutron

(c) anion

(d) electron

(e) atom

2.

Rutherford carried out experiments in which a beam of alpha particles was directed at a thin piece of metal foil. From these experiments he concluded that:

(a) electrons are massive particles.

(b) the positively charged parts of atoms are moving about with a velocity approaching the speed of light.

(c) the positively charged parts of atoms are extremely small and extremely heavy particles.

(d) the diameter of an electron is approximately equal to that of the nucleus.

(e) electrons travel in circular orbits around the nucleus.

3.

Consider the species ⁷²Zn, ⁷⁵As and ⁷⁴Ge. These species have:

(a) the same number of electrons.

(b) the same number of protons.

(c) the same number of neutrons.

(d) the same number of protons and neutrons.

(e) the same mass number.

4.

The neutral atoms of all of the isotopes of the same element have

(a) different numbers of protons.

(b) equal numbers of neutrons.

(c) the same number of electrons.

(d) the same mass numbers.

(e) the same masses.

5.

What is the atomic weight of a hypothetical element consisting of two isotopes, one with mass = 64.23 amu (26.0%), and one with mass = 65.32 amu?

(a) 65.3 amu

(b) 64.4 amu

(c) 64.9 amu

(d) 65.0 amu

(e) 64.8 amu

6.

Naturally occurring rubidium consists of just two isotopes. One of the isotopes consists of atoms having a mass of 84.912 amu; the other of 86.901 amu. What is the percent natural abundance of the heavier isotope?

(a) 15%

(b) 28%

(c) 37%

(d) 72%

(e) 85%

7.

What is the frequency of light having a wavelength of 4.50 x 10^-6 cm?

(a) 2.84 x 10^-12 s^-1

(b) 2.10 x 10⁴ s^-1

(c) 4.29 x 10¹⁴ s^-1

(d) 1.06 x 10²² s^-1

(e) 6.67 x 10¹⁵ s^-1

8.

The emission spectrum of gold shows a line of wavelength 2.676 x 10^-7 m. How much energy is emitted as the excited electron falls to the lower energy level?

(a) 7.43 x 10^-19 J

(b) 5.30 x 10^-20 J

(c) 6.05 x 10^-19 J

(d) 3.60 x 10^-20 J

(e) 5.16 x 10^-20 J

9.

Which of the responses contains all the statements that are consistent with the Bohr theory of the atom (and no others)?

(1) An electron can remain in a particular orbit as long as it continually absorbs radiation of a definite frequency.

(2) The lowest energy orbits are those closest to the nucleus.

(3) An electron can jump from the K shell (n = 1 major energy level) to the M shell (n = 3 major energy level) by emitting radiation of a definite frequency.

(a) 1,2,3

(b) 2 only

(c) 3 only

(d) 1,2

(e) 2,3

10.

The Heisenberg Principle states that _____________.

(a) no two electrons in the same atom can have the same set of four quantum numbers.

(b) two atoms of the same element must have the same number of protons.

(c) it is impossible to determine accurately both the position and momentum of an electron simultaneously.

(d) electrons of atoms in their ground states enter energetically equivalent sets of orbitals singly before they pair up in any orbital of the set.

(e) charged atoms (ions) must generate a magnetic field when they are in motion.

11.

Which statement about the four quantum numbers which describe electrons in atoms is incorrect?

(a) n = principal quantum number, n = 1, 2, 3, ......

(b) l = subsidiary (or azimuthal) quantum number, l = 1, 2, 3, ... , (n+1)

(c) m_l = magnetic quantum number, m_l = (-l), .... , 0, .... , (+l)

(d) m_s = spin quantum number, m_s = +1/2 or -1/2.

(e) The magnetic quantum number is related to the orientation of atomic orbitals in space.

12.

Which atomic orbital is spherical in shape? (Note: you should know and be able to recognize the shapes of the s orbital, p_x, p_y, and p_z orbitals, and d_xy, d_yz, d_xz, d_x2_-y2 and d_z2 orbitals.)

(a) 2s

(b) 3p

(c) 3d

(d) 4f

(e) they are all spherical

13.

The maximum number of electrons that can be accommodated in a sublevel for which l = 3 is:

(a) 2

(b) 10

(c) 6

(d) 14

(e) 8

14.

The ground state electron configuration for arsenic is:

(a) [Ar] 4s² 4p¹³

(b) [Kr] 4s² 4p¹

(c) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹² 4s² 4p¹

(d) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸ 4p⁵

(e) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³

15.

Which of the following electron configurations is correct for nickel?

(a) [Ar] 4s¹ 3d⁸

(b) [Kr] 4s¹ 4d⁸

(c) [Kr] 4s¹ 3d⁸

(d) [Kr] 4s² 3d⁸

(e) [Ar] 4s² 3d⁸

16.

The outer electronic configuration ns²np⁴ corresponds to which one of the following elements in its ground state?

(a) As

(b) Ca

(c) Cr

(d) Br

(e) S

17.

In the ground state of a cobalt atom there are _____ unpaired electrons and the atom is _____.

(a) 3, paramagnetic

(b) 5, paramagnetic

(c) 2, diamagnetic

(d) 0, diamagnetic

(e) 2, paramagnetic

18.

Which one of the following sets of quantum numbers could be those of the distinguishing (last) electron of Mo?

(a) n = 4, l = 0, m_l = 0, m_s = +1/2

(b) n = 5, l = 1, m_l = 9, m_s = -1/2

(c) n = 4, l = 2, m_l = -1, m_s = +1/2

(d) n = 5, l = 2, m_l = +2, m_s = -1/2

(e) n = 3, l = 2, m_l = 0, m_s = +1/2

19.

How many p electrons are there in an atom of rubidium?

(a) 12

(b) 18

(c) 24

(d) 9

(e) 6

20.

A neutral atom of an element has 2 electrons in the first energy level, 8 in the second energy level and 8 in the third energy level. This information does not necessarily tell us:

(a) the atomic number of the element.

(b) anything about the element's chemical properties.

(c) the total number of electrons in s orbitals.

(d) the total number of electrons in p orbitals.

(e) the number of neutrons in the nucleus of an atom of the element.

Answers:

1. (a) 2. (c) 3. (c) 4. (c) 5. (d) 6. (b) 7. (e) 8. (a) 9. (b) 10. (c) 11. (b) 12. (a) 13. (d) 14. (e) 15. (e) 16. (e) 17. (a) 18. (c) 19. (b) 20. (e)

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