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.
Answer:
B. 26amu
Explanation:
The nucleus of an atom in an element contains protons, electrons and neutrons. The proton number equals the electron number in a neutral atom. The proton number is also called the atomic number, denoted by Z.
The mass number also called Atomic mass unit (amu) in this case, of an element is the sum of the proton number and the neutron number in the atom of that element. The mass number is denoted by A.
Hence, A = Z + N
Where A = Mass number
Z = Proton (atomic number)
N = Neutron number
In this question, N is 11 while Z is 15
Hence, the mass number of the element in the question, in AMU, is 15 + 11 = 26amu.
Are bunchgrass because they form a kind of ecosystem within the prairie.
