Which of the following species is amphoteric? a)hco32- b) hf o c) nh4+ d) p042-

Explanation:

Chemical species which can behave as both acids and bases are known as amphoteric species.

can behave as both acid and base.

can donate H+:

can accept H+ as well:

HF can only behave as acid, as it can only donate H+.

is a conjugate acid of .

is a conjugate base.

a

explanation:

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.