A polyamide was prepared by bulk polymerization of hexamethylene diamine (9.22 g) with adipic acid (11.68 g) at 280 °C. Analysis of the whole reaction product showed that it contained 2.6 × 10−3 mol of carboxylic acid groups. Evaluate the number-average molar mass M – n of the polyamide, and also estimate its weight-average molar mass M – w by assuming that it has the most probable distribution of molar mass.

answer; i do believe the correct answer is (river); /// good luck

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.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8