Physics · Composition and size of nucleus, atomic masses, mass-energy relation, mass defect
Assertion Actual atomic mass is greater than mass number. Reason Mass of protons
Assertion Actual atomic mass is greater than mass number. Reason Mass of protons and neutrons is measured in daltons or atomic mass unit (u) but the mass of each neutron and proton is slightly greater than 1 dalton
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Both Assertion and Reason are incorrect
Step-by-step solution
The mass of a proton is about 1.0073 u and that of a neutron is about 1.0087 u, both slightly greater than 1 u. Since the mass number equals the number of nucleons, the sum of the masses of individual nucleons is greater than the mass number. Although the actual atomic mass is slightly reduced due to binding energy (mass defect), the contribution from the nucleon masses and electrons still makes the actual atomic mass slightly greater than the mass number for most atoms, and the reason directly explains this.
Related MCQs
- The missing particle in the reaction:…
- Statement A: Density of nucleus is independent of its mass number Statement B: Beryllium is used as a moderator in nuclear reactors…
- A nucleus with atomic number and neutron number N undergoes two decay processes. The result is a nucleus with atomic number Z-3 and neutron …
- Starting with a sample of pure of its decays into in 15 min. The corresponding half-life is…
- If there are nuclear particles in a nucleus of radius then the number of nuclear particles in radius will be…