Nuclear Physics

Which two elements are fissible?

• U-235 and Pu-244

• U-238 and Pu-239

• U-235 and Pu-239

• U-238 and Pu-244

What is a.m.u. expressed in MeV?

• 930.4

• 931.6

• 932.5

• 931.5

Which of the following substances can be used as a moderator in a nuclear reactor?

• Boron

• Concrete

• Uranium-238

• Water

The Rutherford scattering experiment led to

• the discovery of the electron.

• the quark model of hadrons.

• the discovery of the nucleus.

• evidence for wave-particle duality.

A pure sample of nuclide X containing N nuclei has an activity A. The half-life of X is 6000 years. A pure sample of nuclide Y containing 3N nuclei has an activity 6A. What is the half-life of nuclide Y?

• 1000 years

• 3000 years

• 12 000 years

• 18 000 years

In the Rutherford scattering experiment most α particles passed through the foil undeflected. What is a correct deduction from this result?

• Most of the mass of an atom is within the nucleus.

• The diameter of the nucleus is much less than the diameter of the atom.

• The nucleus has a positive charge.

• The charge of the atom is neutral.

β particles are emitted from a radioactive source in a school laboratory. What is correct for these particles?

• A strong magnetic field will not deflect them.

• They are absorbed by aluminium.

• They do not damage human tissue.

• Their range in air is shorter than that of α particles.

A radioactive source contains a nuclide which has a half-life of 12 hours. A detector placed near the source records an average count rate of 180 counts per minute. The average background count rate is 20 counts per minute. What will be the average count rate after 24 hours?

• 40 counts per minute

• 45 counts per minute

• 50 counts per minute

• 60 counts per minute

The power output of a nuclear reactor is provided by nuclear fuel which decreases in mass at a rate of 4.0 × 10^-6  kg per hour. What is the maximum possible power output of the reactor?

• 28 kW

• 50 MW

• 100 MW

• 200 MW

The moderator of some nuclear reactors is made from graphite. What is the principal purpose of the graphite?

• to absorb all the heat produced

• to decrease the speed of neutrons

• to absorb α and β radiation

• to prevent the reactor from going critical