Astudent dissolved a sample in hexane, spotted it on to a tlc plate and eluted using ethyl acetate. after visualizing the tlc plate under a uv lamp, the student found their sample had two spots corresponding to rf values of 0.31 and 0.85. they ran the tlc plate again, this time dissolving the compound in dicholoroacetic acid and using ethyl acetate as the eluent. what will be the rf values for each spot? -0.55 and 0.81 -0 and 0 -0.31 and 0.85

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.

can you attach the

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )