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d- and f-Block Elements · Question 38

JEE Main 2025 (Online) 29th January Morning ShiftNumericalEasy📈 Topic in 19% papers+4
1

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.

Answer

160

Solution

Fusion of chromite ore with sodium carbonate in free access of air:

4FeCr2O4 + 8Na2CO3 + 7O2 8Na2CrO4 + 2Fe2O3 + 8CO2

Na2CrO4 is water soluble (it is extracted with water); Fe2O3 is the water-insoluble product.

Molar mass of Fe2O3 = 2 56 + 3 16

= 112 + 48 = 160 g mol-1

Answer: 160

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2

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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3

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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4

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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5

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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