Janet learned in science class that the amount of salt that can dissolve in a certain amount of water depends on the temperature of the water. she decides to do an experiment to test this. she carefully adds salt, 100 mg at a time, to a cup of water and stirs until all the salt dissolves. when she has added so much salt that it will not dissolve after 5 minutes, she measures the temperature of the water. she records the temperature and the final amount of salt. she does this with cold water, cool water, room-temperature water, warm water, and hot water. what is the test variable (independent variable) in this experiment?

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.