The internal reaction temperature (in other words, the temperature of the reaction mixture inside the reaction flask) of this diels-alder experiment may be specified by the term reflux. a. what was the internal reaction temperature, in °c? b. how was the internal reaction temperature achieved and maintained?

Solution : (a) The internal reaction temperature required for Diels-alder reaction is . At this temperature, the bonds are broken and rearranged.

(b) Internal reaction temperature is achieved and maintained by heating the flask continously. And also maintained by using heating mantle or sand bath.

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.