Question

Which of the following can be said about the sum of the masses of the subatomic particles in an atom's nucleus?

A-THE SUM IS ALWAYS THE SAME AS THE MASS OF THE ATOM
B-THE SUM IS ALWAYS LESS THAN THE MASS OF THE ATOM
C-THE SUM IS ALWAYS MORE THAN THE MASS OF THE ATOM
D-THE SUM IS ALWAYS ZERO

Answer 1

The sum is always the same. Protons and neutrons both weigh 1au. Electrons have negligible mass, so you can count them as 0.

Answer 2

Answer: The correct answer is Option A.

Step-by-step explanation:

There are 3 subatomic particles in an atom: Neutrons, electrons and protons.

Neutrons and protons reside in the nucleus of an atom.

Mass number of an atom is defied as the sum of number of neutrons and number of protons.

`\text{Mass Number}=\text{Number of neutrons + Number of protons}`

Thus, The sum of neutrons and protons will always be equal to the mass of an atom.

Hence, the correct answer is Option A.