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Which of the following sets includes all the species that will change the orange colour of \( \mathrm{K_2Cr_2O_7} \) in acidic medium?

The correct statement among the following are:
A. \( \mathrm{Mo(VI)} \) and \( \mathrm{W(VI)} \) are less stable than \( \mathrm{Cr(VI)} \).
B. \( \mathrm{Ce^{4+}} \) and \( \mathrm{Tb^{4+}} \) are oxidant while \( \mathrm{Eu^{2+}} \) and \( \mathrm{Yb^{2+}} \) are reductant.
C. \( \mathrm{Cm} \) and \( \mathrm{Am} \) have seven unpaired electrons.
D. Actinoid contraction is greater from element to element than lanthanoid contraction.
Choose the correct answer from the option given below:

Given below are two statements:
Statement I: The number of pairs among \( [\mathrm{Al_2O_3}, \mathrm{Cr_2O_3}], [\mathrm{Cl_2O_7}, \mathrm{Mn_2O_7}], [\mathrm{Na_2O}, \mathrm{V_2O_3}] \) and \( [\mathrm{CO}, \mathrm{N_2O}] \) that contain oxides of same nature (acidic, basic, neutral or amphoteric) is \( 4 \).
Statement II: Among \( \mathrm{Na_2O}, \mathrm{Al_2O_3}, \mathrm{CO} \) and \( \mathrm{Cl_2O_7} \), the most basic and acidic oxides are \( \mathrm{Na_2O} \) and \( \mathrm{Cl_2O_7} \), respectively.
In the light of the above statements, choose the correct answer from the options given below:

\( \mathrm{MnO_4^{2-}} \), in acidic medium, disproportionate to:

"\( X \)" 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:

Given below are two statements:
Statement-I: The number of pairs among \( [\mathrm{Ti}^{4+}, \mathrm{V}^{2+}] \), \( [\mathrm{V}^{2+}, \mathrm{Mn}^{2+}] \), \( [\mathrm{Mn}^{2+}, \mathrm{Fe}^{3+}] \) and \( [\mathrm{V}^{2+}, \mathrm{Cr}^{2+}] \) in which both ions are coloured is \( 3 \).
Statement-II: The number of pairs among \( [\mathrm{La}^{3+}, \mathrm{Yb}^{2+}] \), \( [\mathrm{Lu}^{3+}, \mathrm{Ce}^{4+}] \) and \( [\mathrm{Ac}^{3+}, \mathrm{Lr}^{3+}] \) ions in which both are diamagnetic is \( 3 \).
In the light of the above statements, choose the correct answer from the options given below:

Among the following oxides of \( 3d \) elements, the number of mixed oxides are _________ .
\( \mathrm{Ti_2O_3} \), \( \mathrm{V_2O_4} \), \( \mathrm{Cr_2O_3} \), \( \mathrm{Mn_3O_4} \), \( \mathrm{Fe_3O_4} \), \( \mathrm{Fe_2O_3} \), \( \mathrm{Co_3O_4} \)

Consider \( |x| \) is the difference in oxidation states of \( \mathrm{Mn} \) in highest manganese fluoride and highest manganese oxide. The ions with \( |x| \) number of unpaired electrons from the following are:
A. \( \mathrm{Sc}^{3+} \) B. \( \mathrm{Zn}^{2+} \) C. \( \mathrm{V}^{2+} \) D. \( \mathrm{Fe}^{2+} \) E. \( \mathrm{Co}^{2+} \)
Choose the correct answer from the options given below:

Consider the following reactions.

$ \text{PbCl}_2 + \text{K}_2\text{CrO}_4 \rightarrow \text{A} + 2\text{KCl} $

(Hot solution)

$ \text{A} + \text{NaOH} \rightleftharpoons \text{B} + \text{Na}_2\text{CrO}_4 $

$ \text{PbSO}_4 + 4\text{CH}_3\text{COONH}_4 \rightarrow (\text{NH}_4)_2\text{SO}_4 + \text{X} $

In the above reactions, A, B and X are respectively.

The correct statements among the following are.
A. Basic vanadium oxide is used in the manufacture of \( \text{H}_2\text{SO}_4 \)
B. The spin-only magnetic moment value of the transition metal halide employed in Ziegler-Natta polymerization is \( 2.84 \) BM.
C. The p-block metal compound employed in Ziegler-Natta polymerization has the metal in \( +3 \) oxidation state.
D. The number of electrons present in the outer most ‘d’ orbital of metal halide employed in Wacker process is \( 8 \).

Given below are some of the statements about \( \mathrm{Mn} \) and \( \mathrm{Mn_2O_7} \). Identify the correct statements.
A. \( \mathrm{Mn} \) forms the oxide \( \mathrm{Mn_2O_7} \), in which \( \mathrm{Mn} \) is in its highest oxidation state.
B. Oxygen stabilizes the \( \mathrm{Mn} \) in higher oxidation states by forming multiple bonds with \( \mathrm{Mn} \).
C. \( \mathrm{Mn_2O_7} \) is an ionic oxide.
D. The structure of \( \mathrm{Mn_2O_7} \) consists of one bridged oxygen.
Choose the correct answer from the options given below:

Identify the metal ions among \( \mathrm{Co^{2+}, Ni^{2+}, Fe^{2+}, V^{3+}} \) and \( \mathrm{Ti^{2+}} \) having a spin-only magnetic moment value more than \( 3.0 \, \mathrm{BM} \). The sum of unpaired electrons present in the high spin octahedral complexes formed by those metal ions is _____ .

Given below are two statements:

Statement I: The number of pairs, from the following, in which both the ions are coloured in aqueous solution is \( 3 \).

\( [\mathrm{Sc^{3+}},\, \mathrm{Ti^{3+}}] \), \( [\mathrm{Mn^{2+}},\, \mathrm{Cr^{2+}}] \), \( [\mathrm{Cu^{2+}},\, \mathrm{Zn^{2+}}] \) and \( [\mathrm{Ni^{2+}},\, \mathrm{Ti^{4+}}] \)

Statement II: The \( \mathrm{Th^{4+}} \) is the strongest reducing agent among \( \mathrm{Th^{4+}} \), \( \mathrm{Ce^{4+}} \), \( \mathrm{Gd^{3+}} \) and \( \mathrm{Eu^{2+}} \).

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

Number of paramagnetic ions among the following d- and f-block metal ions is ________.
\( \text{Mn}^{2+}, \text{Cu}^{2+}, \text{Zn}^{2+}, \text{Yb}^{2+}, \text{Sc}^{3+}, \text{La}^{3+}, \text{Gd}^{3+}, \text{Lu}^{3+}, \text{Ti}^{4+}, \text{Ce}^{4+} \).
(Atomic number of Mn \( = 25 \), Cu \( = 29 \), Zn \( = 30 \), Yb \( = 70 \), Sc \( = 21 \), La \( = 57 \), Gd \( = 64 \), Lu \( = 71 \), Ti \( = 22 \), Ce \( = 58 \))

\( X \) and \( Y \) are the number of electrons involved, respectively during the oxidation of \( \mathrm{I^-} \) to \( \mathrm{I_2} \), and of \( \mathrm{S^{2-}} \) to \( \mathrm{S} \) by acidified \( \mathrm{K_2Cr_2O_7} \). The value of \( X + Y \) is ________.

Which of the following is NOT a physical or chemical characteristics of interstitial compounds?

Given below are two statements for catalytic properties of transition metals.
Statement-I: First row transition metals which act as catalyst utilise their \( 3d \) electrons only for formation of bonds between reactant molecules and atoms on the surface of catalyst.
Statement-II: There is increase in the concentration of reactants on the surface of catalyst which strengthens the bonds in reacting molecules.
In the light of the above statements, choose the correct answer from the options given below:

The oxidation state of chromium in the final product formed in the reaction between KI and acidified \( \mathrm{K_{2}Cr_{2}O_{7}} \) solution is:

Given below are two statements:
Statement I: The first ionization enthalpy of Cr is lower than that of Mn.
Statement II: The second and third ionization enthalpies of Cr are higher than those of Mn.
In the light of the above statements, choose the correct answer from the options given below:

Pairs of elements with the same number of electrons in their respective \( 4f \) orbital are:

[Atomic number: \( \text{Eu-}63 \), \( \text{Gd-}64 \), \( \text{Dy-}66 \), \( \text{Ho-}67 \), \( \text{Tm-}69 \), \( \text{Yb-}70 \), \( \text{Lu-}71 \), \( \text{Hf-}72 \)]

A. (Eu and Gd) B. (Dy and Ho)
C. (Yb and Hf) D. (Lu and Tm)

Choose the correct answer from the options given below:

Correct statements from the following are:

A. Potassium dichromate is an oxidizing agent and it oxidises \( \mathrm{FeSO_4} \) to \( \mathrm{Fe_2(SO_4)_3} \) in acidic medium.

B. Sodium dichromate can be used as primary standard in volumetric estimation.

C. \( \mathrm{CrO_4^{2-}} \) and \( \mathrm{Cr_2O_7^{2-}} \) are interconvertible in aqueous solution by varying the \( \mathrm{pH} \) of the solution.

D. \( \mathrm{Cr\!-\!O\!-\!Cr} \) bond angle in \( \mathrm{Cr_2O_7^{2-}} \) is \( 126^\circ \)

Choose the correct answer from the options given below:

Consider the following reactions:

\( \mathrm{NaCl + K_2Cr_2O_7 + H_2SO_4 \rightarrow A + KHSO_4 + NaHSO_4 + H_2O} \)
\( \mathrm{A + NaOH \rightarrow B + NaCl + H_2O} \)
\( \mathrm{B + H_2SO_4 + H_2O_2 \rightarrow C + Na_2SO_4 + H_2O} \)

In the product ‘C’, ‘X’ is the number of \( \mathrm{O_2^{2-}} \) units, ‘Y’ is the total number oxygen atoms present and ‘Z’ is the oxidation state of Cr. The value of \( X + Y + Z \) is __________.

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JEE Main 2026 23rd Jan Evening Shift

The oxidation state of chromium in the final product formed in the reaction between KI and acidified \( \mathrm{K_{2}Cr_{2}O_{7}} \) solution is: