Atomic structure

For each question choose the answer you consider to be the best.

1. Which is the correct definition of the atomic number of an atom?

A. The total number of neutrons and protons in the nucleus of an atom

B. The total number of neutrons, protons and electrons in an atom

C. The number of electrons in the outer energy level of an atom

D. The number of protons in the nucleus of an atom

2. What is the symbol for a species that contains 8 protons, 9 neutrons and 10 electrons?

A. N^3-

B. F^-

C. F^-

D. O^2-

3. How many protons, neutrons and electrons are present in an atom of ⁴⁰Ar?

4. Which statement about isotopes is correct?

A. Isotopes have the same molecular formula but a different structural formula.

B. Isotopes have the same number of neutrons in atoms of the element

C. Isotopes of atoms of the same element have the same electron configuration.

D. Isotopes of atoms of the same element have the same mass number.

5. Which species represents a pair of isotopes?

A. W and X

B. X and Y

C. X and Z

D. W and Z

6. An atom of thorium has a mass number of 234. Which is correct concerning the atomic number
for this isotope and the number of neutrons in its nucleus?

7. What is the difference between the two neutral atoms Np and Pu ?

A. The number of protons, neutrons and electrons

B. The number of protons and electrons only

C. The number of protons and neutrons only

D. The number of neutrons only

8. What is the number of electrons in one Ca²⁺ ion?

A. 40

B. 20

C. 22

D. 18

9. The relative atomic mass of bromine is 79.9. It consists of two isotopes ⁷⁹Br and ⁸¹Br.
What is the percentage of ⁸¹Br in a sample of naturally occurring bromine?

A. 40%

B. 45%

C. 50%

D. 55%

10. The two isotopic abundances of element Z are 90% of Z and 10% of Z.
What is the relative atomic mass of Z?

A. 39.10

B. 39.90

C. –39.50

D. 19

11. Which is correct for the mass and charge of the sub-atomic particle concerned?

12. In what order do the orbitals increase in energy within the same level?

A.d < f < p < s

B.f < d < p < s

C.s < p < d < f

D.s < d < p < f

13. An element shows three peaks in its mass spectrum below.
What is the relative atomic mass of the element?

A. 23.0

B. 24.6

C. 25.0

D. 25.7

14. Which ion will be deflected the most in a mass spectrometer?

A. ¹²C⁺

B. ¹³C⁺

C. ¹²C²⁺

D. ¹³C²⁺

15. Which atoms have one or more unpaired electrons in their ground state?

I. Copper

II. Chromium

III. Zinc

A. I and II only

B. I andIII only

C. II and III only

D. I, II and III

16. Which is correct about the infrared and ultraviolet regions of the spectrum?

17. Which process produces the first line in the visible region of the electromagnetic spectrum
for the emission spectrum of hydrogen?

A. The absorption of energy by electrons

B. The release of energy by electrons

C. The deflection of energy by electrons

D. The convergence of energy by electrons

18. Which are correct for the hydrogen emission spectrum?

I. The spectrum consists of lines converging at higher energy.

II. The lines in the UV region are due to electronic transitions to the lowest
energy level.

III. The lines are due to electrons absorbing energy as they move from
higher energy levels to lower energy levels.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

19. What is the electron configuration of an S^2- ion?

A. 1s²2s²2p⁴

B. 1s²2s²2p⁶

C. 1s²2s²2p⁶3s²3p⁶

D. 1s²2s²2p²

20. Which all contain the same electron configuration?

A. O^2-, Ne, Cl⁺

B. Ca⁺, K⁺, Ar

C. O²⁺, F⁺, Ne

D. Al³⁺, Na⁺, Mg²⁺

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