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d- and f-Block Elements · Question 12

JEE Main 2026 (Online) 2nd April Morning ShiftMCQEasy📈 Topic in 19% papers+4−1
1

Which of the following sets includes all the species that will change the orange colour of K2Cr2O7 in acidic medium ?

  1. Fe2+, Sn2+, I-, S2-
  2. S2-, Fe3+, I-, C2O42-
  3. Fe2+, NO2-, SO2, Sn4+
  4. Fe3+, SO42-, S2-, Sn4+

Answer

(1) Fe2+, Sn2+, I-, S2-

Solution

Acidified K2Cr2O7 is an oxidising agent; its orange colour changes to green only when it is reduced:

Cr2O72- + 14H+ + 6e- 2Cr3+ + 7H2O

So every species in the set must be a reducing agent (able to be oxidised).

(1) Fe2+ Fe3+, Sn2+ Sn4+, I- I2, S2- S — all are oxidised ✓

(2) Fe3+ is already in its higher stable oxidation state and cannot be oxidised ✗

(3) Sn4+ cannot be oxidised further ✗

(4) Fe3+, SO42- (S = +6) and Sn4+ cannot be oxidised ✗

Answer: (1)

JEE Main 2026 (Online) 2nd April Morning Shift

Keep practising — d- and f-Block Elements

2

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 2nd April Evening Shift
3

Among Fe2+, Fe3+, Cr2+ and Zn2+, the ion that shows positive borax bead test and with highest ionisation enthalpy is :

  1. Fe2+
  2. Zn2+
  3. Cr2+
  4. Fe3+
JEE Main 2026 (Online) 2nd April Evening Shift
4

Number of paramagnetic ions among the following d- and f-block metal ions is . Mn2+, Cu2+, Zn2+, Yb2+, Sc3+, La3+, Gd3+, Lu3+, Ti4+, Ce4+ (Atomic number of Mn = 25, Cu = 29, Zn = 30, Yb = 70, Sc = 21, La = 57, Gd = 64, Lu = 71, Ti = 22, Ce = 58)

JEE Main 2026 (Online) 2nd April Evening Shift
5

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

  1. Statement I is false but Statement II is true
  2. Both Statement I and Statement II are false
  3. Both Statement I and Statement II are true
  4. Statement I is true but Statement II is false
JEE Main 2026 (Online) 28th January Morning Shift
6

Consider the following statements about manganate and permanganate ions. Identify the correct statements. Choose the correct answer from the options given below :

  1. A and D Only
  2. A, B and C Only
  3. A, C and D Only
  4. A, D and E Only
JEE Main 2026 (Online) 28th January Evening Shift
7

"X" is an oxoanion of the lightest element of group 7 (in the periodic table). The metal is in +6 oxidation state in "X". The color of the potassium salt of X is

  1. purple
  2. orange
  3. yellow
  4. green
JEE Main 2026 (Online) 24th January Evening Shift
8

The oxidation state of chromium in the final product formed in the reaction between KI and acidified K2Cr2O7 solution is :

  1. +2
  2. +3
  3. +4
  4. +6
JEE Main 2026 (Online) 23rd January Evening Shift
9

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Statement I is true but Statement II is false
  2. Both Statement I and Statement II are true
  3. Both Statement I and Statement II are false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 22nd January Evening Shift
10

Among the following oxides of 3d elements, the number of mixed oxides are . Ti2O3, V2O4, Cr2O3, Mn3O4, Fe3O4, Fe2O3, Co3O4

JEE Main 2026 (Online) 22nd January Evening Shift
11

MnO42-, in acidic medium, disproportionates to :

  1. MnO4- and MnO
  2. MnO4- and MnO2
  3. Mn2O7 and MnO2
  4. Mn2O7 and MnO
JEE Main 2026 (Online) 21st January Morning Shift

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