Question

For the radioactive atom ${}^{99}Tc,$ what is the correct number of protons and neutrons?

• A. $43$ protons and $56$ neutrons
• B. $43$ protons and $99$ neutrons
• C. $56$ protons and $43$ neutrons
• D. $56$ protons and $99$ neutrons

Answer 1

The correct option is A $43$ protons and $56$ neutrons

the full atomic symbol for this isotope of technicium is - ${}_{43}^{99}Tc$ superscript (the mass number) represents the total number of protons and neutrons, and the subscript (the atomic number) represents just the number of protons, has 43 protons and 99 - 43 = 56 neutrons.