Which of the following is true about electron energy shells?

• A. They represent regions around the nucleus in which the electrons orbit.
• B. The shells closest to the nucleus contain electrons with higher energy.
• C. They contain electrons of the same energy.
• D. a and b only.
• E. a and c only.

Answer: (A)

Verified step by step guidance

1. Understand the concept of electron energy shells: Electron energy shells, also known as electron orbitals, are regions around the nucleus of an atom where electrons are likely to be found. These shells are organized in layers, with each shell having a specific energy level.
2. Analyze the statement 'They represent regions around the nucleus in which the electrons orbit': This statement is true. Electrons are found in orbitals around the nucleus, and these orbitals are organized into shells.
3. Evaluate the statement 'The shells closest to the nucleus contain electrons with higher energy': This statement is false. Electrons in shells closer to the nucleus actually have lower energy compared to those in shells further away.
4. Consider the statement 'They contain electrons of the same energy': This statement is false. Electrons within the same shell have similar energy levels, but different shells have different energy levels.
5. Determine which options are correct based on the analysis: Option 'a' is correct, as it accurately describes electron energy shells. Option 'c' is incorrect, so 'a and c only' is not valid. Therefore, the correct answer is 'a and b only', as 'b' is incorrect.