Question

Which would react chemically by forming a covalent bond?

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A. 2 neon atoms with 8 valence electrons each
B. 2 hydrogen atoms with 1 valence electron each
C. 1 magnesium atom with 2 valence electrons and 1 sulfur atom with 6 valence electrons
D. 1 beryllium atom with 2 valence electrons and 1 argon atom with 8 valence electrons

Answer 1

2 hydrogen atom with  1 valence electron   each (answer B) will react forming a covalent bond.

covalent bond is a chemical bond that come  by sharing of one or more electron pair  between two atoms. when two hydrogen atoms react, they form a covalent bond by sharing electrons among themselves.