1.
The center of an atom, containing the protons and neutrons is called:
Correct Answer
D. Nucleus
Explanation
The center of an atom, called the nucleus, contains the protons and neutrons. Protons have a positive charge, while neutrons have no charge. Electrons, on the other hand, orbit around the nucleus and have a negative charge. Therefore, the correct answer is nucleus.
2.
The number of protons in an atom is called the:
Correct Answer
B. Atomic Number
Explanation
The number of protons in an atom determines its atomic number. The atomic number represents the identity of an element and is unique to each element on the periodic table. It determines the element's chemical properties and its position in the periodic table. The other options mentioned in the question, such as Adrionic Number, Atomic Nucleus, and Average Mass Number, do not accurately describe the concept of the number of protons in an atom.
3.
The sum of the numbers of neutrons and protons in the nucleus of an atom is called the:
Correct Answer
C. Mass Number
Explanation
The mass number of an atom is the sum of the numbers of neutrons and protons in its nucleus. It represents the total mass of the atom and is often denoted by the symbol A. The atomic number, on the other hand, represents the number of protons in the nucleus of an atom. The other options, "Adrionic Number" and "Atomic Nucleus," are not correct terms used in atomic structure.
4.
Atoms with the same number of protons but different numbers of neutrons are called:
Correct Answer
A. Isotopes
Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This variation in the number of neutrons results in isotopes having different atomic masses. Isotopes can have different physical and chemical properties, but they still belong to the same element due to their identical number of protons.
5.
A collection of atoms that all have the same number of protons are called:
Correct Answer
B. Elements
Explanation
The correct answer is "Elements" because elements are defined by the number of protons they have in their atomic nucleus. Each element has a unique number of protons, which determines its atomic number and distinguishes it from other elements on the periodic table. Isotopes, on the other hand, are atoms of the same element that have different numbers of neutrons. Pions and quarks are subatomic particles that make up protons and neutrons, but they are not collections of atoms.
6.
An atom with a nucleus that is not stable is called:
Correct Answer
D. Radioactive Isotope
Explanation
A radioactive isotope refers to an atom with an unstable nucleus. The instability is caused by an excess of either protons or neutrons, which leads to the emission of radiation in order to achieve a more stable state. This emission can occur through various processes such as alpha decay, beta decay, or gamma decay. The term "radioactive" indicates that the atom undergoes radioactive decay, releasing energy and particles in the process. Therefore, a radioactive isotope is the correct answer for an atom with a nucleus that is not stable.
7.
Which is larger, an electron or a proton?
Correct Answer
B. Proton
Explanation
The proton is larger than the electron. Protons are subatomic particles found in the nucleus of an atom, while electrons orbit around the nucleus. Protons have a mass of approximately 1 atomic mass unit, while electrons have a much smaller mass of about 0.0005 atomic mass units. Therefore, in terms of size, the proton is larger than the electron.
8.
Which is negatively charged?
Correct Answer
A. Electron
Explanation
An electron is negatively charged because it carries a negative charge of -1. In an atom, electrons orbit around the nucleus, which is made up of protons and neutrons. Protons, on the other hand, carry a positive charge of +1. The negative charge of electrons and the positive charge of protons balance each other out, creating a neutral atom. However, if an atom gains or loses electrons, it becomes an ion with a positive or negative charge. In the case of an electron, it is negatively charged.
9.
What causes the nuclear force?
Correct Answer
C. Exchange of Pions
Explanation
The nuclear force is caused by the exchange of pions. Pions are subatomic particles that are involved in the strong nuclear force, which binds protons and neutrons together in the atomic nucleus. The exchange of pions between nucleons creates a strong attractive force that overcomes the electrostatic repulsion between protons. This force is responsible for holding the nucleus together and is crucial for the stability of atoms.
10.
The nuclear force is a short-range force because quarks can only exist for a short time.
Correct Answer
B. False
Explanation
The nuclear force is a short-range force because it is mediated by particles called mesons, which have a finite range of interaction. Quarks, on the other hand, are fundamental particles that make up protons and neutrons. They do not exist for a short time, but rather are always present within these particles. Therefore, the statement that the nuclear force is short-range because quarks can only exist for a short time is incorrect. The nuclear force is short-range due to the properties of the mediating particles, not the quarks themselves.
11.
Choose the correct number of protons, electrons, and neutrons in the atom 48Ca.
Correct Answer
B. 20 protons, 20 electrons, 28 neutrons
Explanation
The correct answer is 20 protons, 20 electrons, 28 neutrons. The atomic number of an element is determined by the number of protons in its nucleus, so 20 protons indicates that the element is calcium (Ca). Since atoms are electrically neutral, the number of electrons is also 20. The mass number of an element is the sum of its protons and neutrons, so 20 protons and 28 neutrons give a mass number of 48, which matches the given atom 48Ca.
12.
Choose the correct number of protons, electrons, and neutrons in the atom 124Sn.
Correct Answer
C. 50 protons, 50 electrons, 74 neutrons
Explanation
The atomic number of an element represents the number of protons in its nucleus. Since tin (Sn) has an atomic number of 50, it means that it has 50 protons. The number of electrons in a neutral atom is equal to the number of protons, so there are also 50 electrons. The atomic mass of an element is the sum of the protons and neutrons in its nucleus. Since the atomic mass of tin is 124, and we know that it has 50 protons, we can subtract 50 from 124 to find the number of neutrons. Therefore, there are 74 neutrons in the atom 124Sn.
13.
Choose the correct number of protons, electrons, and neutrons in the atom 109Ag.
Correct Answer
A. 47 protons, 47 electrons, 62 neutrons
Explanation
The correct answer is 47 protons, 47 electrons, 62 neutrons. This is because the atomic number of an element determines the number of protons and electrons in an atom, and in this case, the atomic number of silver (Ag) is 47. Neutrons do not contribute to the atomic number, so the number of neutrons can vary.
14.
How many Bohr orbits would a model of the 23Na atom have and how many electrons would be on the outermost orbit?
Correct Answer
C. 3 orbits and 1 electron on the outer orbit
Explanation
According to the Bohr model of the atom, electrons occupy specific energy levels or orbits around the nucleus. The number of orbits is determined by the atomic number of the element. In the case of 23Na, which is sodium, it has an atomic number of 11. Each orbit can hold a maximum number of electrons, which is given by the formula 2n^2, where n is the number of the orbit. For sodium, the first orbit can hold 2 electrons, the second orbit can hold 8 electrons, and the third orbit can hold 18 electrons. Therefore, sodium would have 3 orbits, and the outermost orbit would have 1 electron.
15.
Which of the following atoms are isotopes?
144Ce, 144Nd, 144Sm, 145Nd
Correct Answer
B. 144Nd, 145Nd
Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. In this case, the only atoms that are isotopes are 144Nd and 145Nd. They both have the same number of protons (Nd is the symbol for the element neodymium) but different numbers of neutrons (144 and 145 respectively). The other atoms listed (144Ce and 144Sm) do not have the same number of protons as neodymium and therefore are not isotopes.
16.
A radioactive isotope has a half-life of 3 hours. If a scientist has 30 grams of the isotope, how much is left after 15 hours?
Correct Answer
C. 0.9375 grams
Explanation
The half-life of a radioactive isotope is the time it takes for half of the initial amount to decay. In this case, the half-life is 3 hours. After 15 hours, there are 5 half-lives (15 divided by 3) that have passed. Each half-life reduces the amount by half, so after 5 half-lives, the remaining amount is 1/32 (1 divided by 2 raised to the power of 5) of the initial amount. Therefore, 1/32 of 30 grams is 0.9375 grams.
17.
What is the daughter product in the beta decay of 144Ce?
Correct Answer
B. 144Pr
Explanation
In beta decay, a neutron in the nucleus of an atom is converted into a proton, and an electron (beta particle) is emitted. The daughter product is the resulting nucleus after the decay. In this case, the parent nucleus is 144Ce (cerium), and the daughter product is 144Pr (praseodymium).
18.
What is the daughter product in the alpha decay of 220Rn?
Correct Answer
C. 216Po
Explanation
In the process of alpha decay, an alpha particle (which consists of two protons and two neutrons) is emitted from the nucleus of an atom. This results in the formation of a new nucleus, which is the daughter product. In the case of the alpha decay of 220Rn (radon), the daughter product is 216Po (polonium).
19.
What is the daughter product in the gamma decay of 239U?
Correct Answer
A. 239U
Explanation
In the gamma decay of 239U, the daughter product is still 239U. Gamma decay is a type of radioactive decay where a nucleus emits a gamma ray photon without changing its atomic or mass number. Therefore, the daughter product remains the same as the parent nucleus.
20.
If a piece of paper is placed between a radioactive isotope and a person, which kind of radioactive particle will the person be protected from?
Correct Answer
A. AlpHa Particles
Explanation
When a piece of paper is placed between a radioactive isotope and a person, the person will be protected from Alpha Particles. Alpha particles are relatively large and heavy, consisting of two protons and two neutrons. They have a low penetrating power and can be easily stopped by a sheet of paper or a few centimeters of air. Therefore, the paper acts as a barrier and shields the person from the harmful effects of alpha particles.