Question

The atomic number and the mass number of an element M are 25 and 52 respectively.
The number of electrons, protons and neutrons in $M^{2+}$ ion respectively are:

• A. 25, 25 and 27
• B. 25, 27 and 25
• C. 27, 25 and 27
• D. 23, 25 and 27

Answer 1

The correct option is D 23, 25 and 27

Number of electrons = number of protons = atomic number of element M
Number of electrons = 25
Number of electrons in $M^{2+}$ = 23 (the positive charge is due to the loss of electrons)
Number of neutrons = mass number – atomic number
Number of neutrons = 52 - 25 = 27