Which of the following conditions would produce a radioactive isotope? (A) Too many atoms in the sample provided (B) Too many protons and neutrons in the atom (C) Too many electrons in the outer shell of the atom (D) Too many electrons for the number of neutrons in the atom - HSC - SSCE Chemistry - Question 1 - 2005 - Paper 1

To determine which condition leads to a radioactive isotope, consider that isotopes are variations of elements that differ in the number of neutrons. A radioactive isotope typically arises from an imbalance between the number of protons and neutrons. Option (B), 'Too many protons and neutrons in the atom,' suggests an overabundance of these particles, which can lead to instability. This instability results in radioactivity as the atom seeks to achieve a more stable configuration.