Nuclear Fission — Practice Quiz

Question 1

In the fission ²³⁵U + n → ¹⁴⁴Ba + ⁸⁹Kr + xn + Q, x is:

Accepted Answer

3

Answer

1

Answer

2

Answer

0

Question 2

Approximate energy released per fission of U-235:

Accepted Answer

200 MeV

Answer

1 eV

Answer

1 keV

Answer

1 J

Question 3

Moderator in a thermal nuclear reactor is used to:

Accepted Answer

Slow fast neutrons to thermal speeds

Answer

Absorb neutrons

Answer

Increase fission rate of U-238

Answer

Cool the reactor

Question 4

Why is U-235 used in reactors rather than U-238?

Accepted Answer

U-235 is fissile by thermal neutrons; U-238 needs fast neutrons

Answer

U-235 is heavier

Answer

U-238 is more abundant

Answer

U-238 is radioactive

Question 5

Critical mass is:

Accepted Answer

Minimum fissile mass to sustain a chain reaction

Answer

Mass of one nucleus

Answer

Mass of all fission products

Answer

Mass after one half-life