Question 1

Which subatomic particle is responsible for the chemical identity of an element?

Accepted Answer

Proton

Question 2

A neutral atom of chlorine has 17 protons and 18 neutrons. What is its mass number?

Accepted Answer

$$35$$

Question 3

Which statement best describes isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 4

A sample contains 60% $$^{63}Cu ($$atomic mass = 62.93 u) and 40% $$^{65}Cu ($$atomic mass = 64.93 u). What is the average atomic mass of copper in this sample?

Accepted Answer

$$64.13 u$$

Question 5

Which of the following best explains the difference between mass number and atomic mass?

Accepted Answer

Mass number is the sum of protons and neutrons; atomic mass is the weighted average of all isotopes.

Question 6

Which experiment provided evidence for the existence of the nucleus in the atom?

Accepted Answer

Rutherford's gold foil experiment

Question 7

Which nuclear equation correctly represents the beta decay of $$^{14}C$$?

Accepted Answer

$$^{14}C \$$rightarrow ^{14}$$N $$+ ^{0}$$_{-1}e$$

Question 8

Which process releases more energy per nucleon: nuclear fission or nuclear fusion?

Accepted Answer

Nuclear fusion

Question 9

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

$$10$$ grams

Question 10

Which equation relates the energy of a photon to its frequency?

Accepted Answer

$$E = h 
u$$

Question 11

Which equation correctly relates the speed of light, wavelength, and frequency?

Accepted Answer

$$c = \lambda 
u$$

Question 12

Which electron configuration represents a neutral atom of oxygen?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^4$$

Question 13

Which of the following orbital diagrams correctly represents the ground state of carbon?

Accepted Answer

Two electrons paired in each $$1s$$ and $$2s$$ orbital, and one electron in each of two $$2p$$ orbitals

Question 14

Which statement best describes the difference between an ion and an isotope?

Accepted Answer

Ions have different numbers of electrons; isotopes have different numbers of neutrons.

Question 15

Which of the following is NOT a postulate of Dalton's atomic theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 16

A sample contains two isotopes of element X: 70% $$^{35}X ($$mass = 34.97 u) and 30% $$^{37}X ($$mass = 36.97 u). What is the average atomic mass?

Accepted Answer

$$35.57 u$$

Question 17

Which of the following best explains why atomic mass is not a whole number?

Accepted Answer

Atomic mass is the average of the masses of all isotopes, weighted by their abundance.

Question 18

Which of the following is a correct nuclear equation for the fusion of two hydrogen nuclei to form helium?

Accepted Answer

$$^1_1H + ^1$_1H \$$rightarrow ^2$$_1D + ^0$_1\gamma$$

Question 19

Which of the following best describes the experimental evidence for the existence of electrons?

Accepted Answer

Thomson's cathode ray experiment

Question 20

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Unit 3: Atomic Structure, Nuclear Chemistry, and Electronic Structure Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard