Question

Comparing (a) and (b), which of the following statement is true?

• A. Both (a) and (b) have similar boiling point
• B. Compound (b) is more soluble than compound (a)
• C. Compound (a) has lower boiling point than (b)
• D. Compound (b) has higher melting point than (a)

Answer 1

The correct option is D Compound (b) has higher melting point than (a)

Comparing (a) and (b), compound (a) has higher dipole moment because same groups located on the same side of doubly bonded carbon.
Compound (b) has zero dipole moment because the groups are in opposite direction so their doipole moment will get cancel eact other.

Generally, molecules with higher dipole moments have higher intermolecular forces of attraction.

$\text{Boiling point}\propto \text{Dipole moment}$
$\text{Solubility}\propto \text{Dipole moment}$

Thus, compound (a) is more soluble and it has higher boiling point.

Melting point depends on the packing of molecules.
Trans alkenes are packed closely compare to cis isomers.
Thus, trans iosmers have higher melting point.
Hence, compound (b) has higher melting point.
Therefore, option (d) is correct.