The number of protons in an uncharged atom __________.

• A. equals the number of neutrons
• B. varies from isotope to isotope
• C. equals the number of electrons in the outer orbital of the atom
• D. equals the number of electrons

Answer: (D)

Verified step by step guidance

1. Understand that an uncharged atom is electrically neutral, meaning the total positive charge from protons equals the total negative charge from electrons.
2. Recall that protons are positively charged particles found in the nucleus of an atom, while electrons are negatively charged particles that orbit the nucleus.
3. In a neutral atom, the number of protons must equal the number of electrons to balance the charges.
4. Recognize that the number of neutrons can vary in different isotopes of the same element, but this does not affect the charge balance of the atom.
5. Conclude that in an uncharged atom, the number of protons equals the number of electrons, ensuring electrical neutrality.