But- 2 -yne is reacted separately with one mole of Hydrogen as shown below: B ¯ ← liq   NH 3…

But-2-yne is reacted separately with one mole of Hydrogen as shown below:

B¯←liq NH3NaCH3-C≡+H2C-CH3→∆Pd/CA¯

Identify the incorrect statements from the options given below:

A. A is more soluble than B.
B. The boiling point & melting point of A are higher and lower than B respectively.

C. A is more polar than B because dipole moment of A is zero.
D. Br2 adds easily to B than A.

  1. B and C only
  2. B, C and D only
  3. A, C and D only
  4. A and B only

Solution

A: Cis - But-2-ene

B: Trans - But-2-ene

More polar molecules are more soluble in H2O. Hence A >B.

Molecules having higher dipole moments have higher boiling points due to larger intermolecular forces of attraction. More symmetric isomers have higher melting points due to better packing in crystalline lattice & trans isomers are more symmetric than cis. Hence, in case of boiling point it is A>B and in case of melting point it is B>A.

cis-isomer has resultant of dipoles while in trans isomer dipole moments cancel out. 

So, the correct answer is B, C and D only.

 

 

Asked in: JEE Main 2023 (01 Feb Shift 1)

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