Question 21

A carbon atom with fewer neutrons than a neutral carbon atom is known as an isotope.

An isotope is defined as an atom of the same element that has a different number of neutrons. Therefore, a carbon atom with fewer neutrons than the standard carbon-12 isotope is indeed classified as an isotope.

A) Isotope

This option is correct because isotopes are variations of an element that differ in neutron count while maintaining the same atomic number. For carbon, which typically has six neutrons in its most common form, any variant with fewer neutrons qualifies as an isotope.

B) Ion

This option is incorrect because an ion refers to an atom that has gained or lost electrons, resulting in a net charge. The question specifically addresses the number of neutrons, not electrons, so this term does not apply in this context.

C) Both are correct

This option is incorrect because while isotopes are related to differing neutron counts, ions pertain to electron changes. Thus, both cannot be correct since they describe different phenomena.

D) None of the above

This option is also incorrect as it negates the existence of isotopes, which accurately describes a carbon atom with fewer neutrons. Therefore, stating that none of the options are valid is not accurate.

Conclusion

The correct answer is "isotope" because it precisely defines a carbon atom with fewer neutrons. All other options fail to address the question appropriately, either by referring to unrelated concepts or denying the existence of isotopes altogether.