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d- and f-Block Elements · Question 36

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1

The spin-only magnetic moment value of Mn+ ion formed among Ni, Zn, Mn and Cu that has the least enthalpy of atomisation is . (in nearest integer) Here n is equal to the number of diamagnetic complexes among K2[NiCl4], [Zn(H2O)6]Cl2, K3[Mn(CN)6] and [Cu(PPh3)3I]

Answer

0

Solution

Enthalpy of atomisation ( kJ mol-1): Mn 281, Ni 430, Cu 339, Zn 126.

Zn ( 3d104s2) has no unpaired d electron for metallic bonding, its enthalpy of atomisation is the least M = Zn.

Value of n:

K2[NiCl4]: Ni2+ (3d8), Cl- weak field, tetrahedral (sp3) — 2 unpaired electrons, paramagnetic.

[Zn(H2O)6]Cl2: Zn2+ ( 3d10) — diamagnetic.

K3[Mn(CN)6]: Mn3+ (3d4), CN- strong field, t2g4eg0 — 2 unpaired electrons, paramagnetic.

[Cu(PPh3)3I]: Cu+ ( 3d10) — diamagnetic.

n = 2, and the ion is Zn2+ ( 3d10, no unpaired electron).

= nu(nu + 2) = 0(0 + 2) = 0 BM

Answer: 0

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Keep practising — d- and f-Block Elements

2

The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :

  1. Fe < Mn, Ru < Tc and Re < Os
  2. Fe < Mn, Ru < Tc and Os < Re
  3. Mn < Fe, Tc < Ru and Re < Os
  4. Mn < Fe, Tc < Ru and Os < Re
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3

The molar mass of the water insoluble product formed from the fusion of chromite ore (FeCr2O4) with Na2CO3 in presence of O2 is g mol-1.

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4

Consider 'n' is the number of lone pair of electrons present in the equatorial position of the most stable structure of ClF3. The ions from the following with 'n' number of unpaired electrons are Choose the correct answer from the options given below:

  1. B and D Only
  2. A, D and E Only
  3. B and C Only
  4. A and C Only
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5

Which of the following oxidation reactions are carried out by both K2Cr2O7 and KMnO4 in acidic medium? Choose the correct answer from the options given below :

  1. A, B and C Only
  2. C, D and E Only
  3. B, C and D Only
  4. A, D and E Only
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6

The amphoteric oxide among V2O3, V2O4 and V2O5, upon reaction with alkali leads to formation of an oxide anion. The oxidation state of V in the oxide anion is :

  1. + 4
  2. + 5
  3. + 3
  4. + 7
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7

The spin only magnetic moment ( ) value (B.M.) of the compound with the strongest oxidising power among Mn2O3, TiO and VO is B.M. (Nearest integer).

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