Answer: -
¹⁰B
Explanation: -
For ⁹Be,
The atomic number is 4.
The Mass number is 9.
The number of neutrons = mass number - atomic number
= 9 - 4 = 5
For ⁹B,
The atomic number is 5.
The Mass number is 9.
The number of neutrons = mass number - atomic number
= 9-5 = 4
For ¹⁰B,
The atomic number is 5.
The Mass number is 10.
The number of neutrons = mass number - atomic number
= 10-5 = 5
For ¹⁰Be,
TThe atomic number is 4.
The Mass number is 10.
The number of neutrons = mass number - atomic number
= 10-4 = 6
For ¹²C,
The atomic number is 6.
The Mass number is 12.
The number of neutrons = mass number - atomic number
= 12-6 = 6
