Which isotope was chosen as the standard reference for measuring atomic masses?

Correct option is B

The correct answer is (b) Carbon-12.
· Carbon-12 (C-12) is the isotope chosen as the standard reference for measuring atomic masses.
· In 1961, the International Union of Pure and Applied Chemistry (IUPAC) adopted carbon-12 as the standard reference, setting its atomic mass at exactly 12 atomic mass units (amu).
· This choice was made because carbon-12 is a stable and abundant isotope, making it practical for use in scientific calculations and measurements.
· The atomic mass unit (amu) is defined as one twelfth of the mass of a carbon-12 atom, which simplifies the comparison of atomic masses across different elements.
Information Booster:
· Carbon-11: Carbon-11 is a radioactive isotope of carbon used in positron emission tomography (PET) scans for medical imaging. It has a short half-life of about 20 minutes.
· Carbon-12: Carbon-12 is the most abundant isotope of carbon, making up about 98.9% of all carbon on Earth. It is used as the standard reference for atomic masses.
· Carbon-14: Carbon-14 is a radioactive isotope of carbon used in radiocarbon dating to determine the age of archaeological and geological samples. It has a half-life of about 5,730 years.
· Carbon-13: Carbon-13 is a stable isotope of carbon used in various scientific applications, including nuclear magnetic resonance (NMR) spectroscopy. It makes up about 1.1% of all carbon.