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JEE MAIN 2026 · Organic Compounds Containing Halogens

JEE Main 2026 Session 2 Question Paper: 8 Apr, Shift 2 (B.E./B.Tech), question 66

Updated
Single correct+4 / -1Answer matches NTA’s final key

Given below are two statements:

Statement I: Due to increase in van der Waals forces, the order of boiling points is CH3_3CH2_2CH2_2I > CH3_3CH2_2I > CH3_3I.

Statement II: As 1,4-dichlorobenzene (para) is more symmetric, its melting point is higher than 1,2-dichlorobenzene (ortho), however its boiling point is lower than 1,2-dichlorobenzene (ortho).

In the light of the above statements, choose the correct answer from the options given below:

Choose one

Solution

Solution

  • Statement I, true. Along a homologous series, a longer chain means a larger surface and more polarisable electron cloud, so dispersion forces and boiling points rise: propyl > ethyl > methyl iodide.
  • Statement II, true. The symmetric para isomer packs better in the crystal, so it melts much higher (about 53 °C against about −17 °C for ortho). Boiling depends on attractions in the liquid instead: the ortho isomer has a net dipole while the para isomer's cancels, so ortho boils slightly higher (about 180 °C against 174 °C).

Answer: both statements are true.

Answer checked against the official answer key. The solution is our own working.

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