AFOQT Practice Test

What is the smallest number of electrons required to fill the outer shell of a carbon atom?

1. 2

2. 4

3. 6

4. 8

The correct answer is: 4

The correct answer is based on the electronic configuration of the carbon atom, which has six electrons in total. The configuration is 1s² 2s² 2p². In the outer shell (the second shell), carbon has four electrons: two in the s orbital and two in the p orbitals. To achieve a full outer shell, carbon needs a total of eight electrons in that outer shell (as per the octet rule). Therefore, it requires four additional electrons beyond the four already present to fill the outer shell. This understanding of electron configuration and the concept of the octet rule is key in determining the minimum number of electrons needed to complete the outer shell of a carbon atom.