Question

An ion has -2 charge on it which contains 21 neutrons, and atomic mass number 39. What would be the atomic number, no. of electron and proton of that ion?​

Answer 1

A.N:39 P:39 E:39 THIS IS THE ANSWER

Answer 2

Question : The ion of an atom have 2 negative charge. Mass number of the atom is 16 and the number of neutrons are 8.What is the number of electrons in the ion ?

a] 6

b] 7

c] 8

d] 10

Given :

Mass number of the atom = 16

Number of neutrons = 8

Charge of the ion = -2

To Find : Number of electrons in the ion

Solution :

Mass number is given by ,

★ Mass number = Number of protons + Number of neutrons

We have ,  

Mass number = 16

Number of neutrons = 8

⇒ Number of protons + 8 = 16

⇒ Number of protons = 16 - 8

⇒ Number of protons = 8

Number of protons = Number of electrons in neutral atom

⇒ Number of electrons in the given atom (when it is neutral) = 8

We are given that the atom acquired -2 charge on it . This mean the atom has gained 2e⁻. So , Now the electrons in the given ion should be 10  

∴ The Electrons in the given ion is 10

Hence , option(d) is correct.