Question

Which of the following atoms has the same number of neutrons as 9Be?

9B

10B

10Be

12C

Answer 1

Answer : Option B)
`^(10)B`

Explanation : The option which has same number of neutrons as that of
`^(9)Be` is
`^(10)B`

As,
`^(10)B` has 5 neutrons in its atom, the mass number of
`^(10)B` is 10.

So, when it has 5 protons and 5 electrons in it then it would has 5 neutrons which is similar to that of
`^(9)Be`.


`^(9)Be` has 4 protons and 4 electrons in its atom which means it has (9 - 4) = 5 neutrons.

From, the above it is clear that
`^(10)B` is the correct choice amongst the given options.

Answer 2

Answer: -

¹⁰B has the same number of neutrons as ⁹Be

Explanation: -

Mass number of ⁹Be = 9

Atomic number of ⁹Be = 4

Number of neutrons of ⁹Be = mass number - atomic number

= 9 - 4 = 5

Mass number of ¹⁰B = 10

Atomic number of ¹⁰B= 5

Number of neutrons of ¹⁰B= mass number - atomic number

=10 - 5 = 5