Question

answer: how many core electrons does an atom of beryllium (be) contain? a 0 b 1 c 2 d 3 e 4

Explanation:

Step1: Recall beryllium's electron - configuration

Beryllium has an atomic number of 4. Its electron - configuration is 1s²2s².

Step2: Identify core electrons

Core electrons are the electrons in the inner shells. For beryllium, the 1s² electrons are the core electrons. So, the number of core electrons is 2.

Answer:

C. 2