Question

An atom of potassium-37 and an atom of potassium-42 differ in the total number of
a-positrons
b-neutrons
c-electrons
d-protons

Answer 1

Answer : The correct option is, Neutrons.

Explanation :

The given atoms are, $^{37}K$ and $^{42}K$

As from the periodic table, the atomic number of potassium is, 19

In $^{37}K$,

Atomic mass number = 37

Atomic number = 19

Atomic number = Number of electrons = Number of protons = 19

Number of neutrons = Atomic mass number - Atomic number = 37 - 19 = 18

In $^{42}K$,

Atomic mass number = 42

Atomic number = 19

Atomic number = Number of electrons = Number of protons = 19

Number of neutrons = Atomic mass number - Atomic number = 42 - 19 = 23

From this we conclude that the number of protons and electrons are same in given atoms but the number of neutrons are different.

Hence, an atom of potassium-37 and an atom of potassium-42 differ in the total number of Neutrons.