In the reaction
C7H8 X Y Z
Z is
o-bromotoluene
m-bromotoluene
p-bromotoluene
3-bromo-2, 2, 6- trichlorotoluene
The molal freezing point depression constant for benzene (C6H6) is 4.90 K Kg mol-1. Selenium exists as a polymer of the type Sex. When 3.26 g of selenium is dissolved in 226 g of benzene, the observed freezing point is 0.112C lower than that of pure benzene. The molecular formula of selenium is (atomic mass of Se = 78.8 g mol-1).
Se8
Se6
Se4
Se2
Which of the following compounds have highest melting point?
Only I
Only II
I and II
II and III
B.
Only II
Compound (II) is most symmetrical because it has both CH3 groups and Cl atoms p-to each other. Therefore, it fits in the crystal lattice better than the other two isomers and hence it has highest melting point.