Match each element to the number of electrons in its valence shell
Term Definition
Beryllium (Be) A) Two
Carbon (C) B) One
Lithium (Li) C) Four
Boron (B) D) Three

The order above is wrong, match them correctly.

Be= 2, C =4,  Li = 1 and  B=3

Explanation:

The valence shell can be define as the outermost shell of an atom that contains the valence electrons.

Beryllium (Be), electronic configuration; 1s2 2s2, = 2 electrons in its valence shell.

Carbon (C), electronic configuration; 1s2 2s2 2p2, = 4 electrons in its valence shell.

Lithium (Li), electronic configuration; 1s2 2s1 = 1 electron in its valence shell.

Boron (B) , electronic configuration; 1s2 2s2 2p1 = 3 electron in its valence shell.

your answer would be a. 12.5 kg