11. The half-life of a radioactive substance is defined as:
a) The time it takes for half of the radioactive atoms to decay
b) The time it takes for all of the radioactive atoms to decay
c) The time it takes for the radioactive atoms to become stable
d) The time it takes for the radioactive atoms to emit gamma rays
12. The equation E=mc² relates:
a) Energy and mass
b) Energy and velocity
c) Mass and velocity
d) Mass and force
13. The unit of energy in the International System of Units (SI) is the:
a) Joule
b) Newton
c) Watt
d) Kilogram
14. The unit of power in the International System of Units (SI) is the:
a) Joule
b) Newton
c) Watt
d) Kilogram
15. The unit of electric charge in the International System of Units (SI) is the:
a) Ampere
b) Volt
c) Coulomb
d) Ohm
