[Campbell Biology P.79] Based on Figure 2.4 and the accompanying text, which of the followi... | Practice Question

Based on Figure 2.4 and the accompanying text, which of the following statements about a helium atom is correct?

  • A: A helium nucleus contains 2 protons and 2 electrons.
  • B: The electron cloud accurately represents the actual size relationship between the nucleus and electrons.
  • C: The nucleus of a helium atom has a net positive charge.
  • D: Both models in Figure 2.4 show electrons moving in fixed orbits.

Explanation

Figure 2.4 shows a helium nucleus composed of 2 protons and 2 neutrons. Since protons carry a positive charge, the nucleus has a net positive charge. The text also explicitly states that these models are 'not to scale' and 'greatly overestimate the size of the nucleus in relation to the electron cloud'.