Sperm whales are found in oceans around the world and are known to have the largest brain of any organism. The head of a sperm whale takes up about one–third of its body. Another anatomical characteristic of a sperm whale are the hind leg bones circled below. In terms of evolution, which of the following statements best explains why the sperm whale has hind limb bones?

A: Ancestors of the sperm whale had hind legs to walk on land but the legs became useless when they moved to water.

B: Sperm whales began developing hind limbs to escape hunters and then hunting decreased as the population dwindled.

C: Sperm whales have legs when they are young and then they disappear since they are not needed in water.

D: Sperm whales are equipped with leg bones in case they need to move to land some day.

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.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

the dissolution of polymer can be thermodynamically described in 2 steps.

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.