<span>They are used to measure and map effluent and pollution discharges from factories and sewerage plants, and the movement of sand around harbours, rivers and bays. Radioactive materials used for such purposes have short half-lives and decay to background levels within days.</span>
Answer: 134 neutrons are there in the nucleus of Radon-220
Explanation:
Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.
Thus, number of protons = atomic number = 86
Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.
Mass number = Number of protons + Number of neutrons
220 = 86 + Number of neutrons
Number of neutrons = 134
Assuming that the students
worldwide are being considered, because of the extremely large population, this
can be considered as a binomial distribution. A normal distribution is used most
usually as a fair approximation of the binomial. The mean is the expectation,
therefore:<span>
E[x] = np = (16)(0.22) = 3.52
<span>μ = 3.52 </span></span>