d- and f-Block

Consider the following reactions:

$\ce{NaCl + K2Cr2O7 + H2SO4 -> A + KHSO4 + NaHSO4 + H2O}$

$\ce{A + NaOH -> B + NaCl + H2O}$

$\ce{B + H2SO4 + H2O2 -> C + Na2SO4 + H2O}$

In the product ‘C', ‘X' is the number of $\ce{O2^2-}$ units, ‘Y' is the total number of oxygen atoms present and ‘Z' is the oxidation state of Cr. The value of X + Y + Z is .

• (A)Mn forms the oxide $\ce{Mn2O7}$ in which Mn is in its highest oxidation state.
• (B)Oxygen stabilizes the Mn in higher oxidation states by forming multiple bonds with Mn
• (C)$\ce{Mn2O7}$ is an ionic oxide.
• (D)The structure of $\ce{Mn2O7}$ consists of one bridged oxygen.

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 :

Among the following oxides of 3d elements, the number of mixed oxides is .

$\ce{Ti2O3}$, $\ce{V2O4}$, $\ce{Cr2O3}$, $\ce{Mn3O4}$, $\ce{Fe3O4}$, $\ce{Fe2O3}$, $\ce{Co3O4}$

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.

[$\ce{Sc^{3+}}$, $\ce{Ti^{3+}}$], [$\ce{Mn^{2+}}$, $\ce{Cr^{2+}}$], [$\ce{Cu^{2+}}$, $\ce{Zn^{2+}}$] and [$\ce{Ni^{2+}}$, $\ce{Ti^{4+}}$]

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

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

• (A)The geometry of both manganate and permanganate ions is tetrahedral.
• (B)The oxidation states of Mn in manganate and permanganate are $+7$ and $+6$, respectively.
• (C)Oxidation of Mn(II) salt by peroxodisulphate gives manganate ion as the final product.
• (D)Manganate ion is paramagnetic and permanganate ion is diamagnetic.
• (E)Acidified permanganate ion reduces oxalate, nitrite and iodide ions.

Given below are two statements :

Statement-I : Among Zn, Mn, Sc and Cu, the energy required to remove the third valence electron is highest for Zn and lowest for Sc.

Statement-II : The correct order of the following complexes in terms of CFSE is

$\ce{[Co(H2O)6]^2+}$ $<$ $\ce{[Co(H2O)6]^3+}$ $<$ $\ce{[Co(en)3]^3+}$.

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 .

$\ce{Mn^2+}$, $\ce{Cu^2+}$, $\ce{Zn^2+}$, $\ce{Yb^2+}$, $\ce{Sc^3+}$, $\ce{La^3+}$, $\ce{Gd^3+}$, $\ce{Lu^3+}$, $\ce{Ti^4+}$, $\ce{Ce^4+}$

(Atomic number of Mn = 25, Cu = 29, Zn = 30, Yb = 70, Sc = 21, La = 57, Gd = 64, Lu = 71, Ti = 22, Ce = 58)

• (A)Mo(VI) and W(VI) are less stable than Cr(VI).
• (B)$\ce{Ce^{4+}}$ and $\ce{Tb^{4+}}$ are oxidant while $\ce{Eu^{2+}}$ and $\ce{Yb^{2+}}$ are reductant.
• (C)Cm and Am have seven unpaired electrons.
• (D)Actinoid contraction is greater from element to element than lanthanoid contraction.

• (A)Potassium dichromate is an oxidising agent and it oxidises $\ce{FeSO4}$ to $\ce{Fe2(SO4)3}$ in acidic medium.
• (B)Sodium dichromate can be used as primary standard in volumetric estimation.
• (C)$\ce{CrO4^2-}$ and $\ce{Cr2O7^2-}$ are interconvertible in aqueous solution by varying the pH of the solution.
• (D)Cr–O–Cr bond angle in $\ce{Cr2O7^2-}$ is 126$^\circ$.

Pairs of elements with the same number of electrons in their respective 4f orbital are

[Atomic number, Eu-63, Gd-64, Dy-66, Ho-67, Tm-69, Yb-70, Lu-71, Hf-72]

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

• (A)$\ce{Sc^3+}$
• (B)$\ce{Zn^2+}$
• (C)$\ce{V^2+}$
• (D)$\ce{Fe^2+}$
• (E)$\ce{Co^2+}$

Given below are two statements :

Statement-I : Presence of large number of unpaired electrons in transition metal atoms results in higher enthalpies of their atomisation.

Statement-II : $d_{xy} = d_{xz} = d_{yz} < d_{x^2-y^2} = d_{z^2}$ and $d_{x^2-y^2} = d_{z^2} < d_{xy} = d_{xz} = d_{yz}$ are the d-orbital splittings in $\ce{[Fe(H2O)6]^{3+}}$ and $\ce{[Ni(Cl)4]^{2-}}$ complex ions respectively.

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

• (A)Basic vanadium oxide is used in the manufacture of $\ce{H2SO4}$.
• (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.

• (A)$\Delta_\mathrm{i}H_1$ : Cr $>$ Mn
• (B)$\Delta_\mathrm{i}H_2$ : Cr $>$ Mn
• (C)$\Delta_\mathrm{i}H_1$ : Mn $>$ Cr
• (D)$\Delta_\mathrm{i}H_2$ : Mn $>$ Cr

Given below are two statements :

Statement I : The number of pairs among [$\ce{Ti^4+}$, $\ce{V^2+}$], [$\ce{V^2+}$, $\ce{Mn^2+}$], [$\ce{Mn^2+}$, $\ce{Fe^3+}$] and [$\ce{V^2+}$, $\ce{Cr^2+}$] in which both ions are coloured is 3.

Statement II : The number of pairs among [$\ce{La^3+}$, $\ce{Yb^2+}$], [$\ce{Lu^3+}$, $\ce{Ce^4+}$] and [$\ce{Ac^3+}$, $\ce{Lr^3+}$] ions in which both are diamagnetic is 3.

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

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 option given below :