Nuclear Chemisty

Which of the following particles can pass through paper? I. alpha II. beta III. gamma

II and III only

The graph below shows the quantity of an unknown isotope versus time. What is the half-life of this isotope?

10 years

Which of the following reactions is a fusion reaction?

1H2 + 1H3 2He4

The half-life of uranium-235 is 713 million years. Suppose a rock originally had 26 grams of uranium-235. A geologist had the rock tested, and found that it now has only 3.25 grams of uranium-235. Approximately how old is the rock?

2.1 billion years old

Potassium-40 has a half-life of 1.3 billion years. As the potassium-40 isotope decays, it becomes argon. If a rock was formed with 12 g of potassium-40, approximately how long would it take for 75% of the potassium-40 to be replaced by argon?

2.6 billion years

Each radioactive isotope has a specific half-life, or mode and rate of decay. Examine the graph below. What is the half-life of Strontium-90?

28.1 years

Which of the following equations is an example of nuclear fusion?

2H + 3H 4He + neutron

Uranium-238 is a radioactive form of uranium that has a half-life of 4.51 x 109 years. If a scientist has an initial sample of 700 g of uranium-238, how much will remain after one half-life?

350 g

Uranium-238 is a radioactive form of uranium that has a half-life of 4.51 x 109 years. If a scientist has an initial sample of 800 g of uranium-238, how much will remain after one half-life?

400 g

Carbon-14 is a radioactive form of carbon that has a half-life of 5730 years. If a scientist has an initial sample of 1,000 g of carbon-14, how much will remain after one half-life?

500 g

Which of the following types of nuclear decay produces particles that are identical to the helium nucleus?

Alpha

Which of the following correctly describes the charge of beta particles and alpha particles?

Alpha particles are positively charged, and beta particles are negatively charged.

Which of the following describes the process of gamma decay?

An excited atom releases a high-energy photon.

What type of radioactive decay involves only the release of high-energy photons and therefore does not change the mass of the radionuclide?

Gamma emission

All elements have isotopes. That is, although all atoms of an element have the same number of protons, some of the atoms have a different number of neutrons. If the nucleus of the isotope is unstable, the isotope is radioactive. Radioactive isotopes have a tendency to undergo spontaneous radioactive decay until they form an atom with a stable nucleus. Which of the following statements is true regarding spontaneous radioactive decay? I. Spontaneous radioactive decay occurs more frequently in atoms with large nuclei, although it can occur in atoms with small nuclei. II. Radioactive decay processes can result in the formation of an alpha particle (helium nucleus) or a beta particle (electron). III. When radioactive isotopes decay, they form atoms of different elements. IV. Radioactive elements can undergo more than one decay, or transmutation, in order to form a stable nucleus.

I, II, III, and IV

Which of the following occurs during radioactive decay?

The mass of the radioisotope decreases.

Which of the following processes take place during nuclear fusion?

Two or more atoms are forced together to form a heavier atom.

Unstable isotopes undergo radioactive decay. What occurs during radioactive decay?

Unstable isotopes release charged particles.

Which of the following is a product of nuclear fusion reactions?

a nucleus with greater mass

A radioactive atom has just undergone nuclear decay. Its mass number is now four less than the original atom. Which type of nuclear decay has occurred?

alpha

hree samples are emitting different types of radiation. Some properties of each radiation type are shown in the table below. Emitted by Composition Mass Penetrability Sample 1 electron or positron 0.00055 AMU stopped by metal or wood Sample 2 high-energy electromagnetic waves zero stopped by thick lead or concrete Sample 3 helium nucleus 4 AMU stopped by clothing or a sheet of paper Which type of radiation is Sample 3 emitting?

alpha particles

High-energy electromagnetic waves are released when an atom undergoes gamma decay. Which of the following is usually ejected simultaneously with gamma radiation

an alpha or beta particle

High-energy electromagnetic waves are released when an atom undergoes gamma decay. Which of the following is usually ejected simultaneously with gamma radiation?

an alpha or beta particle

Radiation can be emitted when the nuclear structure and/or the electron configuration of an atom is changed. Which of the following types of radioactive decay releases an electron from the nucleus?

beta emission

What type of radioactive decay causes the radionuclide to become an element with a higher atomic number?

beta emission

Three samples are emitting different types of radiation. Some properties of each radiation type are shown in the table below. Emitted by Composition Mass Penetrability Sample 1 electron or positron 0.00055 AMU stopped by metal or wood Sample 2 high-energy electromagnetic waves zero stopped by thick lead or concrete Sample 3 helium nucleus 4 AMU stopped by clothing or a sheet of paper Which type of radiation is Sample 1 emitting?

beta particles

What type of particle is released during beta decay?

electron

In stars, hydrogen nuclei combine with each other to form helium and other heavier elements. What is this process called?

fusion

What type of radiation is the most dangerous because it can only be stopped by a thick, dense metal such as lead?

gamma radiation

Three samples are emitting different types of radiation. Some properties of each radiation type are shown in the table below. Emitted by Composition Mass Penetrability Sample 1 electron or positron 0.00055 AMU stopped by metal or wood Sample 2 high-energy electromagnetic waves zero stopped by thick lead or concrete Sample 3 helium nucleus 4 AMU stopped by clothing or a sheet of paper Which type of radiation is Sample 2 emitting?

gamma rays

Which of the following elements is most likely to be used in a nuclear fusion reaction?

hydrogen

Which of the following particles can pass through concrete? I. alpha II. beta III. gamma

none of these

Which of the following uses nuclear fusion?

the reactions in the Sun

During alpha decay, a radioactive atom releases an alpha particle that is equivalent to the nucleus of a helium atom. So, the new atom that is formed should have an atomic number that is___than the original atom.

two less