Which molecule contains a non polar covalent bond? 1) O=C=O 2) C=O 3) Br-Br 4) CCL4

3) Br-Br

Explanation:

Polarity occurs between Two atoms of unequal electronegativities.

since Br-Br contain only one atom ( ie.Bromine), they have equal electronegativity. So they can't be polar.

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.