Question

The formula of a molecule is X2. One molecule of X2 contains 18 protons. If the nucleon
number of X is 19, how many neutrons are there in one atom of X?
(a) 1 (b) 9 (c) 10 (d) 18​

Answer 1

Answer:

10 is the answer and it is absolutely correct

Answer 2

Given,

The formula of a molecule = X2

Number of protons in one molecule of X2 = 18

Nucleon number of X = 19

To find,

The number of neutrons in one atom of X.

Solution,

We can simply solve this numerical problem by using the following process:

Let us assume that the number of neutrons in one atom of X is n.

As per the principles of chemistry;

Nucleon number of an atom

= number of protons + number of neutrons

{Statement-1}

Now, according to the question;

Each molecule of X2 contains 2 atoms of element X.

Also, according to the question;

Number of protons in one molecule of X2 = 18

=>Number of protons in one atom of X = 18/2 = 9

{Equation-1}

Now, according to the question;

Nucleon number of X = 19

=> number of protons + number of neutrons = 19

(according to statement-1)

=> 9 + n = 19

(according to equation-1)

=> n = 10

Hence, each atom of X has 10 neutrons. (Option-C)