Why does the presence of lone pairs contribute to the polarity of a water molecule? they allow the bonds between oxygen and hydrogen to be single. they increase the partial positive charge on the oxygen atom. they prevent the atoms from forming a linear molecule. they counter the uneven pull on electrons between the atoms.

The correct answer is "They prevent the atoms from forming a linear molecule. "

The lone pair of electrons on the O atom of the H₂O molecule repels the bond pair of electrons in the O-H bond. Thus causing H₂O to acquire a bent structure instead of a liner structure. If H₂O were a linear molecule the dipole of the each O-H bond would cancel out each other. However, in a bent structure each O-H bond contributes to the overall dipole of the H₂O molecule. Thus contributing to the polarity of a water molecule.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

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