Question

The number of neutrons present in 19K39 is:
a) 39
b) 19
c) 20
d) None of these​

Answer 1

Answer: 20

Explanation:

Z = 19 and A = 39 as per atomic weight definition.

 A = Z + n°

 n° = A - Z  

 n° = 39-19

 n° = 20

Answer 2

Answer:

The number of neutrons present in the potassium is ‘20’.

Explanation:

The given element is ‘K’ potassium.

Atomic number = 19

Mass number = 39

Total number of protons in an atom is considered as the atomic number of that element.

Total number of protons and neutrons in atom is considered as the mass number of that element.

The formula of neutrons number is as follows.

Number of neutrons = mass number - atomic number

                          = 39 - 19 = 20

Therefore, number of neutrons present in the potassium is ‘20’.