A certain element has several isotopes.
Which statement about these isotopes is correct?
A They must have different numbers of electrons orbiting their nuclei.
B They must have the same number of neutrons in their nuclei.
C They must have the same number of nucleons in their nuclei.
D They must have the same number of protons in their nuclei.
A very important experiment increased scientists’ understanding of the structure of matter. In the experiment, particles scattered as they passed through a thin metal foil. Which particles were used, and to which conclusion did the experiment lead?
A particles = alpha particles; conclusion = matter is made up of atoms
B particles = alpha particles; conclusion = atoms have a very small nucleus
C particles = beta particles; conclusion = matter is made up of atoms
D particles = beta particles; conclusion = atoms have a very small nucleus
Below are four statements about isotopes of a certain element.
Which statement about the isotopes must be correct?
A They are radioactive.
B They are unstable.
C They have the same number of neutrons.
D They have the same number of protons.
The scattering of α-particles by a thin metal foil supports the nuclear model of an atom.
Why are α-particles used rather than neutrons?
A because they always travel more slowly
B because they are larger in diameter
C because they are heavier
D because they have a positive charge
The arrangement shown is used to check whether the flour inside a cardboard packet is above a certain level. If it is above this level, the flour absorbs the radiation from the source so that it doesn’t reach the detector.
Which type of radiation is suitable to use?
A α-particles only
B β-particles only
C either α-particles or β-particles
D γ-rays only
A radioactive nucleus contains 128 nucleons. It emits a β-particle.
How many nucleons are now in the nucleus?
A 124
B 127
C 128
D 129
Which diagram could represent the structure of a neutral atom?
A
B
C
D
A reading is taken every 10 minutes of the number of emissions per second from a radioactive source. The table shows the readings.
What is the half-life of the source?
A 10 min
B 20 min
C 40 min
D 60 min
A radioactive decay can be represented as shown.
The equation is incomplete. In this decay, the nucleus changes by:
A absorbing a neutron.
B absorbing a proton.
C emitting an α-particle.
D emitting a β-particle.
The graph shows how the decay rate of a radioactive source changes with time.
What will be the decay rate at 8 days?
A 0 decays/s
B 125 decays/s
C 250 decays/s
D 500 decays/s
Sodium-24 decays to magnesium-24 according to the equation shown. What is the emitted particle?
A α-particle
B β-particle
C neutron
D proton
A radioactive nucleus emits either an α-particle or a β-particle.
What are the products of these two types of radioactive emission?
A product after α-emission = a nucleus of a different element ; product after β-emission = a nucleus of a different element.
B product after α-emission = a nucleus of a different element ; product after β-emission = a nucleus of the same element.
C product after α-emission = a nucleus of the same element ; product after β-emission = a nucleus of a different element.
D product after α-emission = a nucleus of the same element ; product after β-emission = a nucleus of the same element.
Radioactive materials should be handled carefully.
Which safety precaution does not reduce the risk to people using a radioactive material?
A keeping the material a long distance from people
B keeping the material at a low temperature
C using lead screening between the material and people
D using the material for only a short time
A scientist carries out an experiment using a sealed source which emits β-particles. The range of the β-particles in the air is about 30 cm.
Which precaution is the most effective to protect the scientist from the radiation?
A handling the source with long tongs
B keeping the temperature of the source low
C opening all windows in the laboratory
D washing his hands before leaving the laboratory
A beam of γ-rays passes between two charged metal plates as shown in the diagram.
How do the γ-rays pass between the two charged plates?
A The rays are deflected in a direction perpendicular to the page
B The rays are deflected towards the negative plate.
C The rays are deflected towards the positive plate
D The rays will continue in the same direction.
A radioactive source emits three types of radiation R, S and T. The diagram shows an experiment set up to study the penetrating properties of R, S and T.
Which types of radiation are R, S and T?
A R = α-particles; S = β-particles; T = γ-rays.
B R = α-particles; S = γ-rays; T = β-particles.
C R = β-particles; S = α-particles; T = γ-rays.
D R = γ-rays; S = β-particles; T = α-particles.
The half-life of a radioactive substance is 10 minutes. A sample of the radioactive substance contains 2000 nuclei.
How many radioactive nuclei were in the sample half an hour earlier?
A 250
B 4000
C 6000
D 16000
The graph shows the activity of a radioactive source over a period of time.
A 0.5 hours
B 1 hour
C 1.5 hours
D 3 hours
Why are some radioactive sources stored in boxes made from lead?
A Lead absorbs emissions from the radioactive sources.
B Lead decreases the half-life of radioactive sources.
C Lead increases the half-life of radioactive sources.
D Lead repels emissions from the radioactive sources.
A radioactive nucleus emits a β-particle.
What happens to the proton number (atomic number) of the nucleus?
A It stays the same
B It increases by 1
C It decreases by 2
D It decreases by 4
Which shows the relative ionising effects and penetrating abilities of α-particles and β-particles?
A ionising effect - α greater than β; penetrating ability - α greater than β.
B ionising effect - α greater than β; penetrating ability - α less than β.
C ionising effect - α less than β; penetrating ability - α greater than β.
D ionising effect - α less than β; penetrating ability - α less than β.
A powder contains 400 mg of a radioactive material that emits α-particles. The half-life of the material is 5 days.
What mass of that material remains after 10 days?
A 0 mg
B 40 mg
C 100 mg
D 200 mg
A sample of a radioactive isotope has an initial rate of emission of 128 counts per minute and a half-life of 4 days.
How long will it take for the rate of emission to fall to 32 counts per minute?
A 2 days
B 2 days
C 8 days
D 12 days
Which row describes the nature of α-particles and of γ-rays?
The diagram shows the paths of three different types of radiation, X, Y and Z.
Which row in the table correctly identifies X, Y and Z?
Which row gives the properties of the radiation from radioactive materials?
In a laboratory, a detector of ionising radiation records an average background count rate of 8 counts per second. A radioactive source is now placed close to the detector. The count rate on the detector rises to 200 counts per second.
What is the count rate due to radiation from the radioactive source?
A 25 counts/s
B 192 counts/s
C 200 counts/s
D 208 counts/s
Which statement about α-radiation is correct?
A It is a stream of fast-moving electrons.
B It is a form of electromagnetic radiation.
C It is more highly ionising than γ-radiation.
D It is more penetrating than β-radiation.
A radioactive source produces a count rate on a detector of 1600 counts/s. After 32 hours the count rate has fallen to 100 counts/s. Both count rates have been corrected for background radiation.
A 2.0 hours
B 6.4 hours
C 8.0 hours
D 16 hours
α, β and γ-radiations are emitted by radioactive substances.
Which statement is correct?
A α-radiation consists of charged particles and is the most highly ionising radiation.
B β-radiation consists of charged particles and is the most penetrating radiation.
C β-radiation consists of uncharged particles and is the least highly ionising radiation.
D γ-radiation consists of uncharged particles and is the least penetrating radiation.
Which row shows the nature and the penetrating ability of β-particles?
A radioactive isotope is placed near a detector. The readings on the detector are corrected for background radiation and recorded every hour. The table shows the corrected readings.
What is the half-life of the isotope?
A between 0 and 1 hour
B between 1 hour and 2 hours
C between 2 hours and 3 hours
D between 3 hours and 4 hours
A student investigates how the radiation from a radioactive source changes with time. The table shows the results from the detector used by the student. The experiment is repeated by many other students, who also measure the count rate per minute. The half-life of the source is known to be exactly 2.0 minutes.
Why is the measured count rate always greater than half the previous value?
A Radioactive emissions occur randomly with time.
B The detector used is very close to the source.
C There is background radiation present.
D The radioactive source is decaying.
In a cathode-ray tube, a hot tungsten cathode releases particles by thermionic emission.
What are these particles?
A α-particles
B electrons
C protons
D tungsten atoms
Por favor espera - en proceso…