Question 1

The radioactive isotope ¹⁴C beta- decays to the daughter nucleus

Accepted Answer

In beta decay, a neutron in the nucleus is converted into a proton, emitting a beta particle (electron) and an antineutrino. This increases the atomic number by 1, turning carbon-14 into nitrogen-14.

Question 2

In a nuclear accident such as occurred at Chernobyl, the long- term biological damage is caused by

Accepted Answer

The long-term biological damage from a nuclear accident is primarily due to the ionizing radiation from alpha, beta, and gamma particles, which can damage or alter the DNA and other critical molecules within biological cells.

Question 3

Radon is

Accepted Answer

Radon is a naturally occurring radioactive gas that is produced by the decay of uranium in rocks and soil. It can seep into homes through cracks in floors and walls.

Question 4

¹²C and ¹³C differ in their

Accepted Answer

^12C and ^13C are isotopes of carbon, differing only in the number of neutrons. ^12C has 6 neutrons, while ^13C has 7 neutrons. They have the same number of protons and electrons, which means their chemical behavior is nearly identical.

Question 5

According to most scientists, when did the first hominids-- direct human forbears that were fully separated from the apes-- appear on Earth?

Accepted Answer

The first hominids, which are direct human ancestors, appeared a few million years ago, with evidence suggesting they emerged around 6 to 7 million years ago.

Question 6

At Chernobyl, one of the harmful radioactive isotopes was ¹³¹I, a beta emitter with a halflife of 8 days. Suppose some of this isotope is deposited on a field. What can we say about this field 40 days later?

Accepted Answer

The half-life of I-131 is 8 days. After 40 days, which is 5 half-lives (40/8), the radioactivity level decreases to (1/2)^5 = 1/32 of its original level.

Question 7

Which of the following is classified as "ionizing radiation"?

Accepted Answer

Ionizing radiation includes alpha and beta radiation, gamma rays, and X-rays, as they all have enough energy to remove tightly bound electrons from atoms, thus ionizing them.

Question 8

Of the four fundamental forces that act in the universe, which one supports a book that is at rest on a table?

Accepted Answer

The answer of Of the four fundamental forces that act...

Question 9

The carbon in a certain ancient ax- handle is only 1/8-- one- eighth-- as radioactive as the carbon in living wood. The half- life of ¹⁴C is 6000 years. From these facts we can conclude that

Accepted Answer

The ax-handle is 1/8 as radioactive, which means it has gone through 3 half-lives (since (1/2)^3 = 1/8). Each half-life is 6000 years, so 3 half-lives is 18,000 years.

Question 10

Radioactive dating methods and other dating methods indicate that hominids have been on Earth for about

Accepted Answer

Radioactive dating and other methods suggest that hominids have been on Earth for approximately 5 million years, which aligns with the fossil record of early human ancestors.

Question 11

Which of the following is not one of the four fundamental forces in nature?

Accepted Answer

Frictional force is not one of the four fundamental forces in nature. The four fundamental forces are the weak nuclear force, the gravitational force, the strong nuclear force, and the electromagnetic force.

Question 12

In every nuclear reaction,

Accepted Answer

In every nuclear reaction, the nuclear structure is altered, as it involves changes in the composition or energy state of an atomic nucleus.

Question 13

The graph above shows the decay curve for a certain radioactive substance. The half- life of this substance is approximately

Accepted Answer

The answer of  The graph above shows the decay...

Question 14

Suppose that Al the physicist observes a single radioactive nucleus. The length of time until that particular nucleus decays is

Accepted Answer

The decay of a single radioactive nucleus is a random process governed by quantum mechanics, making it fundamentally unpredictable.

Question 15

Suppose that a certain saber- toothed- tiger contained one gram of ¹⁴C [half- life 6000 years] when it died. The approximate ¹⁴C content of the remains of this tiger 24,000 years later would be

Accepted Answer

The answer of Suppose that a certain saber- toothed- tiger...

Question 16

We cannot predict the precise decay time of a particular radioactive ¹⁴C nucleus because

Accepted Answer

Radioactive decay is a quantum process, and the exact time at which a particular nucleus will decay is inherently uncertain due to the probabilistic nature of quantum mechanics.

Question 17

Two different isotopes of the same element have

Accepted Answer

Isotopes of the same element have the same number of protons and electrons, which determine chemical properties, but differ in the number of neutrons, affecting nuclear properties.

Quiz 14: The Nucleus and Radioactivity: an New Force

The radioactive isotope 14 C beta- decays to the daughter nucleus