Answer:
water, H20
Step-by-step explanation:
From the given choices, only water has two unshared or lone pairs of electrons in its central atom.
The formula of water is:
H₂O
H is hydrogen with 1 electron
O is oxygen with 8 electrons and 6 valence electrons
To form the covalent bond, the 6 valence electrons are involved. Two out of the 6 bonds with the two oxygen.
The remaining 4 gives the two lone pairs.