One kilogram of a polyester with a number-average molar mass M n = 10,000 g mol−1 is mixed with one kilogram of another polyester with a Mn = 30,000 g mol−1. The mixture then is heated to a temperature at which ester interchange occurs and the heating continued until full equilibration is achieved.
1. Assuming that the two original polyester samples and the new polyester, produced by the ester interchange reaction, have the most probable distribution of molar mass, calculate Mn and weight-average molar mass Mw for the mixture before and after the ester interchange reaction.

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.

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