Question

Amongst $H_{2}O$, $H_{2}S$, $H_{2}Se$, and $H_{2}Te$, the one with the highest boiling point is:

• A. $H_{2}O$ because of hydrogen bonding
• B. $H_{2}Te$ because of higher molecular weight
• C. $H_{2}S$ because of hydrogen bonding
• D. $H_{2}Se$ because of lower molecular weight

Answer 1

Answer: (A)

$H_{2}O$ because of hydrogen bonding

$H_{2}O$ has higher melting and boiling point than $H_{2}Te$ due to strong Hydrogen bonds.
Compounds in which molecules one joined to one another by H-Bonds have unusually high B.P & M.P this is due to the fact that, relatively more energy is required to separate these H-Bonded molecules as they enter the liquid or the gaseous state.
$H_{2}Te$ is a single molecule, incapable of forming H-Bonds, whereas water $\left(H_{2}O\right)$ molecules are associated by H-Bonds between them.