17th century Roman doctors believed that urine whitened teeth and also kept them firmly in place. As gross as that sounds, it most have worked because it was used as an active ingredient in toothpaste and mouthwash well into the 18th century. Would you believe it’s still used today? Thankfully, not in its original form! The formula for ammonia is NH3. a) How many mols are in 0.75 g of ammonia?

b) How many molecules of ammonia is this?

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.

answer: i dont know the answer but this might

explanation:

l

there are two significant figures.