What kind of bond forms when two elements share their valence electrons UNEQUALLY (one has a significantly higher electronegativity that the other, two words)

The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.

The number at the end of an isotope’s name is the number.

Which of the following is a physical property flammability heat of combustion solubility and toxicity