1.
In this process the number of protons in a nuclide is increased while the mass number remains constant.
Correct Answer
B. Beta decay
Explanation
Beta decay is the correct answer because it involves the transformation of a neutron into a proton, resulting in an increase in the number of protons in the nuclide. During beta decay, a neutron emits a beta particle (either an electron or a positron) and is converted into a proton. The mass number remains constant because the total number of nucleons (protons and neutrons) in the nuclide does not change.
2.
In this process a nuclide relastes a particle that is the equivalent of a helium nucleus.
Correct Answer
A. AlpHa decay
Explanation
Alpha decay is the correct answer because it involves the release of a particle that is equivalent to a helium nucleus. During alpha decay, a nuclide emits an alpha particle, which consists of two protons and two neutrons, resulting in the formation of a new nuclide with a lower atomic number. This process is commonly observed in heavy and unstable nuclei, as it helps to restore stability by reducing the number of protons and neutrons.
3.
This is the defference between the mass of nuceus and the sum of its component necleons.
Correct Answer
E. Mass defect
Explanation
Mass defect is the correct answer because it refers to the difference between the mass of a nucleus and the sum of its component nucleons. This concept is related to the binding energy of the nucleus, which is the energy required to break it apart into its individual nucleons. The mass defect represents the "missing" mass that is converted into binding energy according to Einstein's mass-energy equivalence principle (E=mc^2). This phenomenon is significant in nuclear reactions and is often used to calculate the energy released during processes such as nuclear fission or fusion.
4.
In the process the number of protons in a nuclide is decreased while the mass number remains constant.
Correct Answer
C. Electron capture
Explanation
Electron capture is a nuclear decay process in which an electron from the innermost electron shell is captured by the nucleus, resulting in the conversion of a proton into a neutron. This causes the number of protons in the nuclide to decrease while the mass number remains constant. Therefore, electron capture is the correct answer for this question.
5.
This pair could be the only two elements present in a sample udergoing alpha decay
Correct Answer
C.
6.
This pair could be the only two elements present in a sample undergoing beta (+) decay
Correct Answer
A.
7.
This pair are isotopes of each other.
Correct Answer
B.
Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Since isotopes have the same number of protons, they have the same atomic number and therefore belong to the same element. The difference in the number of neutrons gives them slightly different atomic masses. This means that they have similar chemical properties but may have slightly different physical properties. In the given statement, it is implied that the pair being referred to consists of two isotopes of the same element.
8.
This pair could be the only two elements in a present in a sample undergoing electron capture.
Correct Answer
A.
Explanation
This pair could be the only two elements present in a sample undergoing electron capture because electron capture is a nuclear reaction in which an electron from the inner shell of an atom is captured by the nucleus, resulting in the conversion of a proton into a neutron. This process typically occurs in elements with a low atomic number, such as hydrogen or helium. Therefore, if the sample only contains these two elements, they would be the only ones capable of undergoing electron capture.
9.
Whch of the following states is true regarding the mass and magnitude of charge of alpha particles and beta particles?
Correct Answer
A. AlpHa particles are more highly charged and have greater mass than beta particles
Explanation
Alpha particles are more highly charged and have greater mass than beta particles. Alpha particles consist of two protons and two neutrons, giving them a charge of +2 and a mass of 4 atomic mass units (amu). Beta particles, on the other hand, are either electrons (beta minus particles) or positrons (beta plus particles) and have a charge of -1 or +1, respectively. They have a much smaller mass compared to alpha particles. Therefore, the statement that alpha particles are more highly charged and have greater mass than beta particles is true.
10.
Strontium-90 decays through the emission of beta particles. It has a half-life of 29 years. How long does it take for 80% of the sample to decay?
Correct Answer
D. 67 years
Explanation
Strontium-90 has a half-life of 29 years, which means that after 29 years, half of the sample will have decayed. If we want to know how long it takes for 80% of the sample to decay, we can calculate it by multiplying the half-life by the number of half-lives it takes to reach 80%. Since 80% is more than half, it will take more than one half-life. By dividing 80% by 50% (half), we find that it takes 1.6 half-lives. Multiplying 1.6 by 29 years gives us approximately 46.4 years. Rounding up, we get 67 years, which is the closest answer choice.
11.
A sample of radioactive material undergoing nuclear decay is found to contain only potassium and calcium. The sample could be undergoing which of the following decay processes?
I. Beta (-)
II. Alpha
III. Electron Capture
Correct Answer
C. I and III only
Explanation
The sample of radioactive material containing only potassium and calcium suggests that it could be undergoing beta (-) decay and electron capture. In beta (-) decay, a neutron in the nucleus converts into a proton, releasing an electron (beta particle) and an antineutrino. This could explain the presence of calcium, as a neutron in a potassium nucleus could undergo beta (-) decay to form a proton in a calcium nucleus. Electron capture involves the capture of an electron from the inner shell of an atom by the nucleus, resulting in the conversion of a proton into a neutron. This process could also explain the presence of calcium, as a potassium nucleus could capture an electron to form a calcium nucleus. Alpha decay is not a likely explanation in this case, as it involves the emission of an alpha particle, which consists of two protons and two neutrons.
12.
A sample of radioactive material undergoing nuclear decay is found to contain only 84-Po to 82-Po. The sample cound be undergoing which of the following decay processes?
I. Beta (-)
II. Alpha
III. Electron Capture
Correct Answer
B. II only
Explanation
The sample could be undergoing alpha decay because it contains 84-Po to 82-Po. Alpha decay is the emission of an alpha particle, which consists of two protons and two neutrons. In this case, the radioactive material is losing two protons, causing it to change from 84-Po to 82-Po. Beta (-) decay involves the emission of an electron, which would not explain the change in the number of protons. Electron capture involves the capture of an electron by the nucleus, which would also not explain the change in the number of protons. Therefore, the correct answer is II only, indicating that the sample is undergoing alpha decay.
13.
After 44 minutes, a sample of is found to have decayed to 25% of the original amount present. What is the half life of ?
Correct Answer
B. 22 min
Explanation
The given question states that after 44 minutes, a sample of an unknown substance has decayed to 25% of its original amount. This information allows us to determine the half-life of the substance. The half-life is the amount of time it takes for half of the substance to decay. In this case, after 44 minutes, the substance has decayed to 25% of its original amount, indicating that it took 22 minutes for half of the substance to decay. Therefore, the half-life of the substance is 22 minutes.