$$\displaystyle \text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Question 1

Which statement best describes isotopes of an element?

Accepted Answer

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

Question 2

Given the isotope notation $$\displaystyle \frac{43}{20} \mathrm{Ca}$$, how many neutrons does this atom have?

Accepted Answer

23

Question 3

What is the atomic number ($$Z) of an $$atom, and what does it determine?

Accepted Answer

The atomic number is the number of protons and determines the chemical properties of the element.

Question 4

For a neutral atom, which relationship is always true?

Accepted Answer

Number of protons $$=$$ Number of electrons

Question 5

Which equation correctly calculates the number of neutrons in an atom?

Accepted Answer

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

Question 6

A neutral atom of $$\$$displaystyle ^{27}$$_{13}\mathrm{Al}$$ has how many electrons?

Accepted Answer

13

Question 7

Which of the following correctly gives the number of subatomic particles for $$\$$displaystyle ^{38}$$_{17}\mathrm{Cl}$$?

Accepted Answer

17 protons, 21 neutrons, 17 electrons

Question 8

If an atom has 54 neutrons, 40 protons, and 40 electrons, what is its mass number?

Accepted Answer

94

Question 9

Which of the following is the correct isotope notation for an atom with 42 protons, 33 neutrons, and 42 electrons?

Accepted Answer

$$\$$displaystyle ^{75}$$_{42}\mathrm{Mo}$$

Question 10

A sample of strontium has an isotope with mass number 88 and atomic number 38. How many neutrons does it have?

Accepted Answer

50

Question 11

Which of the following best explains why isotopes of the same element have different physical properties?

Accepted Answer

They have different numbers of neutrons, which affects their mass.

Question 12

An atom has 46 electrons, 46 protons, and 60 neutrons. What is its mass number?

Accepted Answer

106

Question 13

Which of the following is true for a neutral atom?

Accepted Answer

The number of protons equals the number of electrons.

Question 14

A patient receives a dose of $$\$$displaystyle ^{99}$$_{43}\mathrm{Tc}$$ for a medical scan. How many neutrons are in this isotope?

Accepted Answer

56

Question 15

Which of the following is the correct electron count for a neutral atom of $$\$$displaystyle ^{75}$$_{33}\mathrm{As}$$?

Accepted Answer

33

Question 16

If an atom has a mass number of 27 and 13 protons, what is its neutron count?

Accepted Answer

14

Question 17

Which of the following is the correct representation for an isotope with 44 protons, 42 electrons, and 61 neutrons?

Accepted Answer

$$\$$displaystyle ^{105}$$_{44}\mathrm{Ru}$$

Question 18

A neutral atom of $$\$$displaystyle ^{16}$$_{8}\mathrm{O}$$ has how many neutrons?

Accepted Answer

8

Question 19

Which of the following is the correct number of subatomic particles for $$\$$displaystyle ^{38}$$_{17}\mathrm{Cl}$$?

Accepted Answer

17 protons, 21 neutrons, 17 electrons

Atomic Structure: Isotopes and Subatomic Particles

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