Answers Crowley Credit Recovery Physics BUnit Test

Radioactivity Answers

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Sadira makes a graphic organizer to show how geologists and archaeologists use radioisotopes.Which labels belong in the regions marked X and Y?

X: Uses carbon-14Y: Uses uranium-238

X: Uses uranium-238Y: Determines ages of objects

X: Determines ages of objectsY: Uses uranium-238

X: Uses isotopes with short half-livesY: Determines ages of objects

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Which describes why radioisotopes can be used as tracers in studying the biological and chemical processes of plants?

The radioisotope is chemically identical to the nonradioisotope the plant normally uses.

The radioisotope is absorbed more quickly than the nonradioisotope the plant normally uses.

The radioisotope converts the nonradioisotope normally used by a plant into a radioisotope.

The radioisotope travels through the plant without participating in any chemical processes.

What did the accident at the nuclear power plant in Chernobyl in 1986 demonstrate about the use of nuclear power that had not been previously demonstrated?

The byproducts of the process are radioactive.

The generation of electricity releases no carbon dioxide.

The uranium fuel that is used is radioactive.

Large areas can be contaminated with radiation.

Which are methods of reducing exposure to ionizing radiation? Check all that apply.

using a lead apron during medical X-rays

picking up radioactive material by hand to avoid dropping it

taking an X-ray image of large areas of the body at once

using a short burst of X-rays to take an image

taking an image of the smallest possible area

The half-life of cobalt-60 is 5 years. How old is a sample of cobalt-60 if only one-eighth of the original sample is still cobalt-60?

5 years

10 years

15 years

20 years

Which change occurs when an atom undergoes alpha decay?

The nucleus loses mass and a new element is produced.

The nucleus gains a proton and a new element is produced.

The nucleus loses energy and remains the same element.

The nucleus loses a neutron and remains the same element.

Which is the best predictor of the radioactive nature of an isotope?

the proton-to-electron ratio

the neutron-to-proton ratio

the neutron-to-electron ratio

the electron-to-proton ratio

Calcium-51 has a half-life of 4.5 days. Only 0.75 gram remains of a sample that was initially 12 grams.How old is the sample of calcium-51?

4.5 days

9.0 days

13.5 days

18 days

The table lists several radioisotopes that have technological uses.

uranium-238

carbon-14

iodine-131

technetium-99

A 60-g sample of radioactive isotope is measured after two half-lives have passed. What pair of percentages describes the sample after two half-lives?

50% unchanged and 50% stable

25% unchanged and 75% stable

12.5% unchanged and 87.5% stable

75% unchanged and 25% stable

The half-life of cobalt-60 is 5 years. How old is a sample of cobalt-60 if only one-eighth of the original sample is still cobalt-60?

5 years

10 years

15 years

20 years

The emission of light from a radioisotope occurs during decay.

Answer not available

Gertrude writes a short story in which the main character must enter a nuclear-powered spaceship’s engine room that has lost its shielding in order to prevent the engine from flooding the rest of the ship with radiation. The main character is not wearing protective gear.What effects are best for Gertrude to consider when planning what may happen to the character?

non-stochastic effects such as possible DNA mutations later in life resulting from the short-term, high-level exposure

non-stochastic effects such as severe burns and radiation sickness resulting from the short-term, high-level exposure

stochastic effects such as possible DNA mutations that are unlikely to occur from the single, low-level exposure

stochastic effects such as severe burns and radiation sickness resulting from the long-term, low-level exposure

Carlos arranges his notes about radioactive decay in a graphic organizer. He wants to add the labels shown.Label 1: PhotonLabel 2: PositronLabel 3: No change in mass number

Label 1: ZLabel 2: XLabel 3: Y

Label 1: XLabel 2: ZLabel 3: X

Label 1: XLabel 2: ZLabel 3: Y

Label 1: XLabel 2: ZLabel 3: Z

Which describes why radioisotopes can be used as tracers in studying the biological and chemical processes of plants?

The radioisotope is chemically identical to the nonradioisotope the plant normally uses.

The radioisotope is absorbed more quickly than the nonradioisotope the plant normally uses.

The radioisotope converts the nonradioisotope normally used by a plant into a radioisotope.

The radioisotope travels through the plant without participating in any chemical processes.

[BLANK]

cobalt

uranium

carbon

technetium

Sadira makes a graphic organizer to show how geologists and archaeologists use radioisotopes.Which labels belong in the regions marked X and Y?

X: Uses carbon-14Y: Uses uranium-238

X: Uses uranium-238Y: Determines ages of objects

X: Determines ages of objectsY: Uses uranium-238

X: Uses isotopes with short half-livesY: Determines ages of objects

Which are methods of reducing exposure to ionizing radiation? Check all that apply.

using a lead apron during medical X-rays

picking up radioactive material by hand to avoid dropping it

taking an X-ray image of large areas of the body at once

using a short burst of X-rays to take an image

taking an image of the smallest possible area

What is the half-life of a radioisotope?

half of the time needed for a sample of radioisotope to become stable

the time needed for half of a sample of radioisotope to decay

the time needed before the first half of a radioisotope begins to decay

half of the time needed for a radioisotope to leave the body

Calcium-51 has a half-life of 4.5 days. Only 0.75 gram remains of a sample that was initially 12 grams.How old is the sample of calcium-51?

4.5 days

9.0 days

13.5 days

18 days

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