Read the following statements carefully and identify the incorrect statement:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Bromo, iodo and polychloro derivatives of hydrocarbons are lighter than water.
Bromo, iodo and polychloro derivatives are heavier than water, not lighter.
Option (1) Haloalkanes are slightly soluble in water. — A correct statement. To dissolve, a haloalkane must break the hydrogen bonds between water molecules, and the new attractions it forms with water release less energy.
Option (2) The boiling point of o-dichlorobenzene is higher than p-dichlorobenzene. — A correct statement. The polar ortho isomer has stronger dipole–dipole attractions: b.p. o-isomer 453 K, p-isomer 448 K.
Option (3) Bromo, iodo and polychloro derivatives of hydrocarbons are lighter than water. — The incorrect statement. Density rises with the number and atomic mass of the halogen atoms, so these derivatives are heavier than water.
Option (4) CN- is an ambident nucleophile — A correct statement. It can attack through carbon (KCN gives alkyl cyanides) or through nitrogen (AgCN gives isocyanides).
NCERT (2026-27 edition):
Density
