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d- and f-Block Elements

JEE Main 2025 (Online) 29th January Morning ShiftNumericalEasy📈 Topic in 18% papers+4
Ques. 1JEE Main 2025, 29 January (Morning Shift)

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

Keep practising — d- and f-Block Elements

Ques. 2JEE Main 2025, 28 January (Morning Shift)

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
Ques. 3JEE Main 2025, 28 January (Morning Shift)

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
Ques. 4JEE Main 2025, 28 January (Evening Shift)

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
Ques. 5JEE Main 2025, 28 January (Evening Shift)

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).

Ques. 6JEE Main 2025, 24 January (Morning Shift)

Preparation of potassium permanganate from MnO2 involves two step process in which the 1st step is a reaction with KOH and KNO3 to produce

  1. K3MnO4
  2. K4[Mn(OH)6]
  3. K2MnO4
  4. KMnO4
Ques. 7JEE Main 2025, 24 January (Morning Shift)

Which of the following ions is the strongest oxidizing agent? (Atomic Number of Ce = 58, Eu = 63, Tb = 65, Lu = 71)

  1. Lu3+
  2. Eu2+
  3. Tb4+
  4. Ce3+
Ques. 8JEE Main 2025, 24 January (Evening Shift)

Match List - I with List - II. Choose the correct answer from the options given below :

  1. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
  2. (A)-(II), (B)-(IV), (C)-(I), (D)-(III)
  3. (A)-(III), (B)-(I), (C)-(II), (D)-(IV)
  4. (A)-(IV), (B)-(II), (C)-(III), (D)-(I)
Ques. 9JEE Main 2025, 23 January (Morning Shift)

The correct set of ions (aqueous solution) with same colour from the following is:

  1. V2+, Cr3+, Mn3+
  2. Ti4+, V4+, Mn2+
  3. Sc3+, Ti3+, Cr2+
  4. Zn2+, V3+, Fe3+
Ques. 10JEE Main 2025, 23 January (Evening Shift)

Match List - I with List - II Choose the correct answer from the options given below :

  1. A-IV, B-II, C-III, D-I
  2. A-IV, B-III, C-I, D-II
  3. A-III, B-I, C-IV, D-II
  4. A-III, B-IV, C-II, D-I
Ques. 11JEE Main 2025, 23 January (Evening Shift)

Consider the following reactions K2Cr2O7 [-H2O]KOH [A] [-H2O]H2SO4 [B] + K2SO4 The products [A] and [B], respectively are :

  1. K2Cr(OH)6 and Cr2O3
  2. K2CrO4 and Cr2O3
  3. K2CrO4 and K2Cr2O7
  4. K2CrO4 and CrO

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