1.
The nucleus of a particular form of carbon (chemical symbol
C) contains 6 protons and 7 neutrons. Which of the following is
the correct way to represent it?
Correct Answer
B. B
Explanation
The correct way to represent the nucleus of carbon with 6 protons and 7 neutrons is by using the symbol "C" and writing the sum of protons and neutrons as a superscript to the left of the symbol. Therefore, the correct representation is B.
2.
A particular nuclide of iron (chemical symbol Fe) is representedas follows:
Correct Answer
D. 26 protons
Explanation
The given information states that the nuclide of iron has 26 protons. Protons are positively charged particles found in the nucleus of an atom and determine the atomic number of an element. Since the chemical symbol Fe represents iron, which has an atomic number of 26, it is correct to say that the nuclide of iron has 26 protons.
3.
How many neutrons does this nuclide have?
Correct Answer
30
Explanation
The number given in the question (30) is the answer itself, suggesting that the nuclide being referred to has 30 neutrons.
4.
Which symbol represents a beta particle?
Correct Answer
B. B
Explanation
The symbol for a beta particle is the letter "B". Beta particles are high-energy electrons or positrons that are emitted during radioactive decay. The letter "B" is commonly used to represent beta particles in scientific notation and equations.
5.
Which symbol could represent an alpha particle?
Correct Answer
A. A
Explanation
The symbol "A" could represent an alpha particle. Alpha particles are made up of two protons and two neutrons, which is equivalent to a helium nucleus. The symbol "A" is commonly used in nuclear physics to represent the mass number of an atom, which is the sum of protons and neutrons in the nucleus. Therefore, "A" is a suitable symbol to represent an alpha particle.
6.
A radioactive nuclide X decays according to this equation:
Correct Answer
D. D
7.
A radioactive sample contains 8000 undecayed atoms. It hasa half-life of 4 days. What will be the number of undecayedatoms remaining after 12 days?
Correct Answer
1000
Explanation
The half-life of a radioactive sample is the time it takes for half of the radioactive atoms to decay. In this case, the half-life is 4 days. After 4 days, half of the 8000 undecayed atoms will decay, leaving 4000 undecayed atoms. After another 4 days (8 days total), half of the remaining 4000 undecayed atoms will decay, leaving 2000 undecayed atoms. Finally, after another 4 days (12 days total), half of the remaining 2000 undecayed atoms will decay, leaving 1000 undecayed atoms. Therefore, the number of undecayed atoms remaining after 12 days is 1000.
8.
The graph shows the pattern of decay of a radioactive substance.What is the half-life of the substance?
Correct Answer
8
8 days
Explanation
The correct answer is 8,8 days. This means that the half-life of the radioactive substance is 8 days. In other words, it takes 8 days for half of the substance to decay. The graph likely shows the amount of the substance decreasing over time, and based on the pattern observed, it can be determined that it takes 8 days for the amount to decrease by half.
9.
The graph bellow shows the amount of undecayed material in a sample of a radioactive substance as it decayed. When the material had decayed to a very low level, the detector still recorded background radiation.From the graph, determine the background count rate.
Correct Answer
20
Explanation
The background count rate can be determined by observing the graph. As the material decayed to a very low level, the detector still recorded a count rate of 20. This indicates that even when there is no undecayed material present, the detector still detects a background count rate of 20.
10.
The graph bellow shows the amount of undecayed material in a sample of a radioactive substance as it decayed. When the material had decayed to a very low level, the detector still recorded background radiation.Determine the initial count rate due to the radioactive substance by calculating:initial count rate - background count rate
Correct Answer
100
Explanation
The initial count rate is determined by subtracting the background count rate from the total count rate. In this case, the background count rate is very low, so when it is subtracted from the total count rate, the result is 100. This means that the initial count rate due to the radioactive substance is 100.
11.
Which part of the atom contains most of its mass?
Correct Answer
C. Nucleus
Explanation
The nucleus of an atom contains most of its mass. The nucleus is located at the center of the atom and is made up of protons and neutrons. Protons have a positive charge, while neutrons have no charge. Both protons and neutrons contribute to the mass of the atom, while electrons, which are found in shells or orbits around the nucleus, have negligible mass. Therefore, the nucleus is the correct answer as it contains the majority of the atom's mass.
12.
The diagram shows the paths of some alpha particles as they approached a nucleus of a gold atom.Explain why the alpha particle (1) shown was back-scattered.
Correct Answer
A. It's pushed back repelled by the nucleus when it passes by very near.
Explanation
The alpha particle is back-scattered because it is repelled by the nucleus when it passes by very near. As the alpha particle approaches the gold atom's nucleus, it experiences a strong electrostatic repulsion due to the positive charge of the nucleus. This repulsion causes the alpha particle to change direction and be pushed back in the opposite direction. The closer the alpha particle gets to the nucleus, the stronger the repulsion and the more likely it is to be back-scattered.
13.
The diagram shows the paths of some alpha particles as they approached a nucleus of a gold atom.Explain why the alpha particle (2) shown was undeflected as it passed the gold nucleus.
Correct Answer
C. They have like charges but it's far away from the nucleus.
Explanation
The alpha particle (2) shown was undeflected as it passed the gold nucleus because it is far away from the nucleus. Since both the alpha particle and the gold nucleus have like charges (positive), according to the principles of electrostatics, they should repel each other and the alpha particle should be deflected. However, because the alpha particle is far away from the nucleus, the electrostatic force between them is weak, resulting in no deflection.