Answer:
The decay of radioactive elements occurs at a fixed rate. The half-life of a radioisotope is the time required for one half of the amount of unstable material to degrade into a more stable material. For example, a source will have an intensity of 100% when new. At one half-life, its intensity will be cut into 50% of the original intensity.
Explanation:
3 electrons are located in the 2p level
ANSWER- B
Atomic emission spectra are produced when excited electrons return to the ground state. The emitted light corresponds to energies of the specific electrons.