Which compounds are acting like Brønsted-Lowry acids in the following acid-base equilibrium?

HCO3− + H2O H2CO3 and OH−

H₂O and H₂CO₃  

Explanation:

Per the Brønsted-Lowry theory, an acid is a substance that can donate a proton to another substance.

In the forward reaction, the water acts as a Brønsted-Lowry acid. It donates a proton to the bicarbonate ion and converts it to carbonic acid.  

In the reverse reaction, the carbonic acid acts as a Brønsted-Lowry acid. It donates a proton to the hydroxide ion and converts it to water.  

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.