30. Which subatomic particle has a charge of -1?
Answer: B
The subatomic particle that has a charge of -1 is the electron.
The electron is the only subatomic particle among the options provided that carries a negative charge of -1. This characteristic distinguishes it from the other particles listed.
A) Proton
A proton has a positive charge of +1, which is the opposite of what is asked in the question. Therefore, it cannot be the correct answer as it does not meet the criterion of having a charge of -1.
B) Electron
The electron is indeed the subatomic particle with a charge of -1. Its negative charge is fundamental to its role in atomic structure and chemistry, making it the correct answer to the question.
C) Neutron
Neutrons are electrically neutral, carrying no charge at all. This absence of charge disqualifies them from being the correct answer since they do not have a charge of -1.
D) Quark
Quarks can possess fractional charges, such as +2/3 or -1/3, depending on their type. However, none of the common quarks carry a full charge of -1, making this option incorrect in relation to the question.
Conclusion
The electron is definitively the correct answer because it is the only particle listed with a charge of -1. In contrast, protons, neutrons, and quarks do not satisfy the conditions of the question, as they either carry positive charges or are neutral. This clearly establishes that the electron is unique among the options in having the specified charge.