What type of intermolecular force is likely to occur between two water molecules ($H_{2}O$) or strands of DNA ($\mathrm{DNA}$)?

Which of the following pure compounds can form hydrogen bonds? Which can form hydrogen bonds with water? Which ones do you expect to be soluble in water?

a. (CH₃CH₂)₂NH

b. (CH₃CH₂)₃N

c. CH₃CH₂CH₂OH

d. (CH₃CH₂CH₂)₂OH

Contrary to expectation, the addition of more fluorines to ethane lowers the boiling point. Explain this phenomenon.

In each pair, choose the compound you would expect to have the highest boiling/melting point.

(b)

Which of these phenomena result from hydrogen bonding?

Hydrogen bonds are important for which of the following reasons?

What types of molecular interactions are primarily responsible for the stability of base pairs in $DNA$?

In each pair, choose the compound you would expect to have the highest boiling/melting point.

(a)

In each pair, choose the compound you would expect to have the highest boiling/melting point.

(c)