Question

How many number of neutrons are present in potassium and calcium?

Answer 1

Atomic mass of calcium is 40 amu.

Which means that the number of protons +the number of neutrons inside the nucleus of a calcium atom=40....... (1)

The atomic number of calcium is 20=no of protons.

Let the number of neutrons be x.

x+19=40...... [from (1)]

Therefore number of electrons in calcium=40-20=20.

Similarly atomic mass of potassium=39

And atomic number of potassium=19

Therefore number of neutrons=atomic mass-atomic number

=39-19=20

Answer 2

Number of neutrons in potassium=20

Number of neutrons in calcbium=20