Which of the following statements about the charges and masses of subatomic particles is not true?

Introduction / Context:
Basic knowledge of subatomic particles is essential for understanding atomic structure, chemical bonding, and many areas of physics. Protons, neutrons, and electrons differ in charge and mass, and exam questions often test your ability to recall these differences correctly. This question asks which of the given statements about subatomic particles is not true, meaning it contradicts the accepted model of the atom.

Given Data / Assumptions:

• We consider three main subatomic particles: protons, neutrons, and electrons.
• Protons carry a positive charge, electrons carry a negative charge, and neutrons are neutral.
• Protons and neutrons have comparable masses, while electrons are much lighter.

Concept / Approach:
To solve this, recall the standard properties of subatomic particles. Protons have a charge of plus one in elementary charge units, electrons have minus one, and neutrons have zero charge. Protons and neutrons both reside in the nucleus and have similar masses, roughly 1 atomic mass unit, whereas electrons are about 1/1836 of this mass. The statement that is not true will contradict one of these well established facts, particularly regarding charge or mass relationships between particles.

Step-by-Step Solution:
Step 1: Examine option A: protons and neutrons have the same charge. Protons are positively charged and neutrons are neutral, so this statement is false. Step 2: Examine option B: protons and electrons have opposite charges. Protons are positive and electrons are negative, so this statement is true. Step 3: Examine option C: protons and neutrons have almost the same mass. Both have masses close to 1 atomic mass unit, so this statement is true. Step 4: Option D, all of the above, would imply that all listed statements are true, which is not correct because option A is false. Step 5: Conclude that the statement that is not true is option A.

Verification / Alternative check:
You can verify by recalling the symbols and charges: proton is written as p plus, neutron as n with zero charge, and electron as e minus. Textbooks and reference tables consistently show that neutrons do not carry electric charge. This directly contradicts the idea that protons and neutrons have the same charge. At the same time, standard references confirm that protons and neutrons have nearly equal masses, and that protons and electrons carry equal but opposite charges, confirming that options B and C are correct statements.

Why Other Options Are Wrong:
Option B is accurate because the positive charge of a proton balances the negative charge of an electron in neutral atoms. Option C is accurate because proton and neutron masses are both close to 1 atomic mass unit and are very similar. Option D is wrong because it groups together one false statement with true ones and labels all of them as true. The only statement that is actually not true is option A, which incorrectly describes the charges of protons and neutrons.

Common Pitfalls:
A common mistake is to confuse neutrality with having the same charge as another particle. Some students wrongly think that if a neutron has no charge, it can be grouped with positively charged protons as similar. Another pitfall is to assume that all nuclei particles must have the same properties in terms of charge, which is incorrect. Keeping a clear mental table of the charges and relative masses of protons, neutrons, and electrons helps avoid these errors in exam questions.

Final Answer:
The statement that is not true is protons and neutrons have the same charge.