Q147 / 150 · MHT CET 2007 · Physics
$m_{p}$ and $m_{n}$ are masses of proton and neutron respectively. An element of mass $M$ has $Z$ protons and $N$ neutrons then
- A$M>Z m_{p}+N m_{n}$
- B$M=Z m_{p}+N m_{n}$
- Correct answerC$M < Z m_{p}+N m_{n}$
- D$M$ may be greater than less than or equal to $Z m_{p}+N m_{n}$, depending on nature of element
Solution
When a nucleus is formed, then the mass of nucleus is slightly less than the sum of the mass of $Z$ protons and $N$ neutrons.
ie,
$$
M < \left(Z m_{p}+N m_{n}\right)
$$
Hence, the correct answer is option: 'C'.