Q: Which of the following pairs are isotopes of each other?

$$^{12}\mathrm{C}$$ \,\text{and}\, ^{14}\mathrm{C}$

Q: Which of the following best describes the difference between $$^{1}\mathrm{H}$$ and $$^{2}\mathrm{H} ($$deuterium)?

$$^{2}\mathrm{H}$$ \text{ has one more neutron than } ^{1}\mathrm{H}$

Question 1

Which of the following correctly represents the isotopic symbol for an atom of fluorine with 9 protons and 10 neutrons?

Accepted Answer

$$^{19}\mathrm{F}$$

Question 2

An atom has an atomic number $$Z = 13$$ and a mass number $$A = 27. $$How many neutrons does it contain?

Accepted Answer

$$14$$

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 4

A sample contains two isotopes of element X: $$^{35}\mathrm{X} (75$$%) and $$^{37}\mathrm{X} (25$$%). What is the average atomic mass of element X?

Accepted Answer

$$35.5$$

Question 5

Which of the following best describes the information provided by the atomic number ($$Z) of an $$element?

Accepted Answer

The number of protons in the nucleus

Question 6

A neutral atom of sodium has an atomic number of $$11$$ and a mass number of $$23. $$How many electrons does it have?

Accepted Answer

$$11$$

Question 7

Which of the following is the correct isotopic symbol for an atom with $$20$$ protons, $$20$$ neutrons, and $$20$$ electrons?

Accepted Answer

$$^{40}\mathrm{Ca}$$

Question 8

If an atom has $$15$$ protons, $$16$$ neutrons, and $$15$$ electrons, what is its mass number?

Accepted Answer

$$31$$

Question 9

Which of the following pairs are isotopes of each other?

Accepted Answer

$$^{12}\mathrm{C}$$ \,	ext{and}\, ^{14}\mathrm{C}$

Question 10

A hospital uses a radioactive isotope of iodine, $$^{131}\mathrm{I}$$, for thyroid imaging. How many neutrons are present in one atom of $$^{131}\mathrm{I}$$?

Accepted Answer

$$78$$

Question 11

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of electrons and protons.

Question 12

A certain element has two naturally occurring isotopes: $$^{10}\mathrm{B} (19.9$$%) and $$^{11}\mathrm{B} (80.1$$%). Calculate the average atomic mass of boron.

Accepted Answer

$$10.8$$

Question 13

Which of the following is the correct relationship between mass number ($$A$$), atomic number ($$Z$$), and number of neutrons ($$N$$)?

Accepted Answer

$$A = Z + N$$

Question 14

A neutral atom of element X has $$17$$ protons and $$18$$ neutrons. What is the correct isotopic symbol for this atom?

Accepted Answer

$$^{35}\mathrm{Cl}$$

Question 15

Which of the following statements is true regarding the charge of an atom?

Accepted Answer

A neutral atom has equal numbers of protons and electrons.

Question 16

A sample of magnesium contains three isotopes: $$^{24}\mathrm{Mg} (79$$%), $$^{25}\mathrm{Mg} (10$$%), and $$^{26}\mathrm{Mg} (11$$%). What is the average atomic mass of magnesium?

Accepted Answer

$$24.3$$

Question 17

Which of the following would be the correct isotopic symbol for an atom with $$6$$ protons, $$8$$ neutrons, and $$6$$ electrons?

Accepted Answer

$$^{14}\mathrm{C}$$

Question 18

A scientist discovers a new isotope of oxygen with $$8$$ protons and $$10$$ neutrons. What is the mass number and the correct isotopic symbol?

Accepted Answer

$$^{18}\mathrm{O}$$

Question 19

Which of the following best describes the difference between $$^{1}\mathrm{H}$$ and $$^{2}\mathrm{H} ($$deuterium)?

Accepted Answer

$$^{2}\mathrm{H}$$ 	ext{ has one more neutron than } ^{1}\mathrm{H}$

Question 20

A patient receives a diagnostic scan using $$^{99}\mathrm{Tc}$$, which has $$43$$ protons. How many neutrons are in this isotope?

Accepted Answer

$$56$$

Atomic Structure and Isotopic Symbols: Practice and Concepts

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