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JEE Main 20257 AprilMorning Shift
Exam
JEE Main
Year
2025
Date
7 April
Shift
Morning Shift
Subject
Chemistry
Chapter
d and f Block Elements

JEE Main 2025 · 7 April · Morning Shift · Chemistry · d and f Block Elements

The number of valence electrons present in the metal among Cr, Co,...

The number of valence electrons present in the metal among Cr,Co,Fe\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe} and Ni which has the lowest enthalpy of atomisation is

Options

  1. A88
  2. B99
  3. C66
  4. D1010

Correct answer

C. 66

Step-by-step solution

Out of Cr,Co,Fe\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe} and Ni\mathrm{Ni}
Chromium has lowest heat of atomisation.
Cr=[Ar]3 d54 s1\mathrm{Cr}=[\mathrm{Ar}] 3 \mathrm{~d}^5 4 \mathrm{~s}^1
∵\because Total six valence e−\mathrm{e}^{-}in Cr\mathrm{Cr}.
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