The half-life period of a radioactive element is 10 years. How long it takes to reduce to 12.5% of its original weight?
A.20 years
B.30 years
C.40 years
D.125 years
A.20 years
B.30 years
C.40 years
D.125 years
A.its mass exceeds critical mass
B.its mass is just equal to critical mass
C.its mass is less than critical mass
D.all of these answers.
A.stimulated emission of radiation
B.spontaneous emission of radiation
C.stimulated energetic radiation
D.spontaneous emission of radio waves
A.fourth nation of the world
B.fifth nation of the world
C.sixth nation of the world
D.seventh nation of the world
A.Atomic weight
B.Atomic radius
C.Atomic volume
D.Atomic number
A.neutrons
B.protons
C.electrons
D.mesons
A.protons only
B.protons and electrons
C.protons and neutrons
D.protons neutrons and electrons
A.200 Fermi
B.2 Fermi
C.50 Fermi
D.1000 Fermi
A.radium
B.thorium
C.polonium
D.uranium
A.Cd
B.U
C.Pb
D.Fe