Which of the following correctly defines the mass number of an atom?
Sum of protons and neutrons
The nucleus of an atom contains protons and neutrons, together called nucleons.
The mass number (A) is the total number of nucleons: A = number of protons + number of neutrons.
The number of protons alone is the atomic number, and electrons add almost nothing to the mass.
Hence, the answer is the sum of protons and neutrons.
Similar Questions
According to Bohr’s model, electrons revolve around the nucleus in:
Two isotopes of chlorine are present in nature: chlorine-35 and chlorine-37. Which statement best explains their chemical behavior?
In Rutherford’s α-particle scattering experiment, the conclusion that most of the atom is empty space was drawn because:
Which statement about mass number is correct?
Which of the following best represents the characteristic properties of isotopes?
Which of the following correctly describes a proton?
Imagine a scientist is analyzing an unknown atom and finds it has a mass number of 24 and an atomic number of 12. If the atom gains two neutrons due to a nuclear reaction, what will be its new mass number?
Which of the following statements is/are CORRECT?
Statement I: The maximum number of electrons in any shell is given by 2n2.
Statement II: The third shell (n=3) can hold up to 12 electrons.
Which of the following statements about neutrons is correct?
Which statement best describes the nucleus according to Rutherford's model?
Important Questions from Structure of Atom
- According to Bohr's model, electromagnetic radiations possess dual character properties behaving like:
- Which of the following is NOT an isotope of hydrogen atom?
- The atomic number of an element is equal to which of the following?
- Which of the following factors primarily determines the size of an atom?
- The atomic radius of hydrogen atom is
