A radioactive element is an element which is subject to spontaneous degeneration of its nucleus followed by the emission of alpha, beta and gamma particles. All elements with atomic numbers greater than 83 are radioactive.
The given phrases that describe radioactive elements are-
They have a consistent number of particles
- the particles are alpha, beta and gamma particles.
They have a half-life that determines their rate of decay.
Explanation for other options:
Not all elements occur in nature. Radioactive decay rates may not be constant as the decay happens when a radioactive substance emits a particle. It is not possible to predict exactly when a given atom of a substance will emit a particular particle. When the radioactive element release energy and particles, it decays.
You can't hear sound on the moon because of space. Space is a vacuum so you can't hear anything unless there is a medium for it to travel through (like air)
The law reduced acid rain and improved public health by dramatically reducing emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx).
Explanation:
For solid it could be melting into a liquid
for gas it could be Evaporating into a liquid
