Chemistry Regents Practice Test

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Study for the Chemistry Regents Test. Prepare with flashcards and multiple choice questions, each question has hints and explanations. Master the curriculum and get ready to excel in your exam!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

Which ion has no electrons?

O2-
Na+
H+
Cl-

The correct answer is: H+

The ion that has no electrons is the hydrogen ion, often represented as H+. When a hydrogen atom loses its single electron, it becomes a hydrogen ion, which means it is left with just one proton and no electrons. This results in a charged species with a +1 charge, indicating that it has lost its electron. In contrast, the other ions mentioned retain some electrons. O2- indicates an oxygen atom that has gained two additional electrons, leading to a total of ten electrons (where it originally had eight). Na+ represents a sodium atom that has lost one electron, resulting in ten electrons, as sodium originally has eleven. Similarly, Cl- is a chloride ion that has gained one electron, giving it a total of eighteen electrons while originally having seventeen. Thus, the hydrogen ion (H+) is unique in that it completely lacks electrons, making it the correct answer to the question regarding which ion has no electrons.