Question

Find out the nucleus which are iso neutronic :
a.) $_6^{14}C$, $_7^{15}N$, $_9^{17}F$
b.) $_6^{12}C$, $_7^{14}N$, $_9^{19}F$
c.) $_6^{14}C$, $_7^{14}N$, $_9^{17}F$
d.) $_6^{14}C$, $_7^{14}N$, $_9^{19}F$

Answer 1

Hint:. The iso neutronic species are those which have the same number of neutrons. The number of neutrons can be calculated from the mass number by subtracting the number of protons from it.
Number of neutrons = Mass number - Number of protons (Atomic number)
After knowing the number of neutrons in all species, we can find out about iso neutronic.

Complete step by step answer:
We know that the term ‘iso’ means the same. So, the iso neutronic species are those which have the same number of neutrons.
Now, the question comes; how we can calculate the number of neutrons in a species.
The number of neutrons can be calculated from the mass number. We have been given the mass number and atomic number of all species.
The atomic number is equal to the number of protons and mass number is equal to the sum of the number of neutrons and number of protons.
So, Number of neutrons = Mass number - Number of protons (Atomic number)
So, now let us see all species one by one and find out.
Thus, the first option has $_6^{14}C$, $_7^{15}N$ and $_9^{17}F$.
The first species is $_6^{14}C$.
Mass number of carbon = 14
Atomic number = Number of protons = 6
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 6
Number of neutrons = 8

The nest species in option a.) is $_7^{15}N$.
Mass number of Nitrogen = 15
Atomic number = Number of protons = 7
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 15 - 7
Number of neutrons = 8

The next species is $_9^{17}F$.
Mass number of Nitrogen = 17
Atomic number = Number of protons = 9
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 17 - 9
Number of neutrons = 8
All the species in option a.) contain an equal number of neutrons. So, this could be a possible answer.

The second option given has $_6^{12}C$, $_7^{14}N$ and $_9^{19}F$.
The first species is $_6^{12}C$.
Mass number of carbon = 12
Atomic number = Number of protons = 6
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 12 - 6
Number of neutrons = 6

The next species in option b.) is $_7^{14}N$.
Mass number of Nitrogen = 14
Atomic number = Number of protons = 7
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 7
Number of neutrons = 7

The next species is $_9^{19}F$.
Mass number of Nitrogen = 19
Atomic number = Number of protons = 9
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 19 - 9
Number of neutrons = 10
All the species in option b.) does not contain an equal number of neutrons. So, this could not be a possible answer.

The third option has $_6^{14}C$, $_7^{14}N$ and $_9^{17}F$.
The first species is $_6^{14}C$.
Mass number of carbon = 14
Atomic number = Number of protons = 6
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 6
Number of neutrons = 8

The next species is $_7^{14}N$.
Mass number of Nitrogen = 14
Atomic number = Number of protons = 7
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 7
Number of neutrons = 7

The next species is $_9^{17}F$.
Mass number of Nitrogen = 17
Atomic number = Number of protons = 9
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 17 - 9
Number of neutrons = 8
All the species in option c.) do not contain equal numbers of neutrons. So, this can not be a possible answer.

The fourth option is $_6^{14}C$, $_7^{14}N$and $_9^{19}F$.
The first species is $_6^{14}C$.
Mass number of carbon = 14
Atomic number = Number of protons = 6
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 6
Number of neutrons = 8

The next species is $_7^{14}N$.
Mass number of Nitrogen = 14
Atomic number = Number of protons = 7
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 14 - 7
Number of neutrons = 7

The next species is $_9^{19}F$.
Mass number of Nitrogen = 19
Atomic number = Number of protons = 9
So, Number of neutrons = Mass number - Number of protons
Number of neutrons = 19 - 9
Number of neutrons = 10
All the species in option d.) does not contain an equal number of neutrons. So, this could not be a possible answer.
So, the correct answer is “Option A”.

Note: We know that mass number of sum of masses of nucleons. The nucleons are all the subatomic particles present in the nucleus of an atom. The two subatomic particles present in the nucleus are neutrons and protons. Further, in a chemical symbol, the alphabet describes the element symbol. The subscript with symbol tells the atomic number and superscript tells the mass number.