Question 1

Which of the following statements best describes the nucleus of an atom?

Accepted Answer

It contains most of the atom's mass and all of its positive charge.

Question 2

Which subatomic particle has a mass of approximately $$1.67493 	imes 10$$^{-27}$$ kg and no electrical charge?

Accepted Answer

Neutron

Question 3

An atom is electrically neutral when:

Accepted Answer

The number of protons equals the number of electrons.

Question 4

Which of the following best explains why atoms are considered the building blocks of matter?

Accepted Answer

Atoms are the smallest identifiable unit of an element that retains its properties.

Question 5

If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its net electrical charge?

Accepted Answer

$$0$$

Question 6

Which of the following is true about the electron cloud in an atom?

Accepted Answer

It is the region where negatively charged particles are dispersed.

Question 7

A certain atom has a mass number of 23 and contains 11 protons. How many neutrons does it have?

Accepted Answer

$$12$$

Question 8

Which of the following subatomic particles has a relative charge of $$-1$$ and a mass of $$0.00091 	imes 10$$^{-27}$$ kg?

Accepted Answer

Electron

Question 9

If a neutral atom of a certain element has 20 protons, how many electrons does it have?

Accepted Answer

$$20$$

Question 10

Which of the following best describes the relationship between the charges of a proton and an electron?

Accepted Answer

They are equal in magnitude but opposite in sign.

Question 11

A hospital uses a synthetic element in a diagnostic procedure. Which statement is true about synthetic elements?

Accepted Answer

They are not found naturally and are made by scientists.

Question 12

Which of the following is a correct statement about the mass of subatomic particles?

Accepted Answer

Protons and neutrons have nearly identical masses, much greater than that of electrons.

Question 13

A neutral atom of sodium ($$^{23}_{11}\mathrm{Na}) is $$used in a medical tracer. What is the total number of subatomic particles (protons, neutrons, and electrons) in this atom?

Accepted Answer

$$11$$ protons + $$12$$ neutrons + $$11$$ electrons = $$34$$

Question 14

Which of the following real-world scenarios best illustrates the concept of electrical neutrality in atoms?

Accepted Answer

A helium-filled balloon floats because the helium atoms have equal numbers of protons and electrons.

Question 15

Which equation correctly represents the sum of the charges of a proton and an electron?

Accepted Answer

$$+1 + (-1) = 0$$

Question 16

A scientist discovers a new atom with 15 protons, 16 neutrons, and 15 electrons. What is the atomic number and mass number of this atom?

Accepted Answer

Atomic number = $$15$$, Mass number = $$31$$

Question 17

Which of the following best explains why electrons are not included in the calculation of an atom's mass number?

Accepted Answer

Electrons have a much smaller mass compared to protons and neutrons.

Question 18

A patient receives a radioactive isotope for imaging. The isotope has 53 protons and 74 neutrons. What is its mass number?

Accepted Answer

$$127$$

Question 19

Which of the following is a property of electrical charge demonstrated by subatomic particles?

Accepted Answer

Like charges repel and opposite charges attract.

Question 20

Which of the following best describes the distribution of mass and charge in an atom?

Accepted Answer

Most of the mass and all positive charge are concentrated in the nucleus, while electrons occupy most of the volume.

Atoms and Elements: Structure and Subatomic Particles

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