Calculate no. of neutrons in ${}_{35}^{80}Br$

Question

Accepted Answer

The correct option is (3):

To calculate the number of neutrons in an atom, we use the mass number and the atomic number. The notation ${}_{Z}^{A}X$ represents an isotope, where $X$ is the chemical symbol of the element, $A$ is the mass number, and $Z$ is the atomic number.

In the given notation ${}_{35}^{80}Br$:  * The atomic number ($Z$) is 35. The atomic number represents the number of protons in the nucleus of an atom. For a neutral atom, it also equals the number of electrons.
  * The mass number ($A$) is 80. The mass number represents the total number of protons and neutrons in the nucleus.The number of neutrons can be calculated by subtracting the atomic number from the mass number:
Number of neutrons = Mass number ($A$) - Atomic number ($Z$)
Number of neutrons = $80 - 35 = 45$

Therefore, a bromine atom with a mass number of 80 and an atomic number of 35 contains 45 neutrons.

The incorrect option is (1): 35
This option represents the atomic number, which is the number of protons (and electrons in a neutral atom), not the number of neutrons.

The incorrect option is (2): 80
This option represents the mass number, which is the total sum of protons and neutrons, not just the number of neutrons.

The incorrect option is (4): 7
This option is incorrect as it does not correspond to any fundamental property (protons, electrons, or mass number) derived from the given isotopic notation.