Verified Solution • 2025–26 Session moderate

QJEEM20Ch10ce: JEE Main 2020 Chemistry - Class 12 JEEM20Ch10ce Solution: Complex A has a composition of H 12 O 6 Cl 3 Cr. If the complex …

Complex A has a composition of H12O6Cl3Cr. If the complex on treatment with conc.H2SO4 loses 13.5% of its original mass, the correct molecular formula of A is :
[Given: atomic mass of Cr = 52 amu and Cl = 35 amu]

Multiple Choice Options

  • A [Cr(H2O)5Cl]Cl2.H2O
  • B [Cr(H2O)4Cl2]Cl.2H2O
  • C [Cr(H2O)3Cl3].3H2O
  • D [Cr(H2O)6]Cl3

Step-by-Step Verified Solution

Let x molecule of water are lost then

13.5 = [x×186×18+3×35+52]×100

⇒ x = 1.99 ≃ 2

∴ Around two moles of water are lost during heating.

∴ Formula of complex could be

[Cr(H2O)4Cl2]Cl.2H2O

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