The most common isotope of chromium has a mass number of 52. which notation represents a different isotope of chromium?
a. 52/24cr
b. 54/24cr
c. 24/52cr
d. 24/54cr

Each element symbol has two basic numbers, atomic number and mass. Atomic number, a number in a lower position states the number of protons, which is typical of each element and is unchangeable. Mass number, placed in the upper position, is a total of protons and Neutrons, and is changeable due to difference in Neutrons in the isotopes. Thus, a different isotope of chromium must have the same protons (atomic number), but a different mass number.

Well the best answer would be option B. 54/24Cr

The mass has escaped into a gas which you can not see so the law stays true.

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.