d- and f-Block Elements

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

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

Correct statements from the following are A. Potassium dichromate is an oxidising 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 pH of the solution. D. Cr-O-Cr bond angle in $\mathrm{Cr_2O_7^{2-}}$ is 126°. 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. 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). Choose the correct answer from the options given below:

Consider $|x|$ is the difference in oxidation states of 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:

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

The correct statements among the following are. A. Basic vanadium oxide is used in the manufacture of $\mathrm{H_2SO_4}$. 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. Choose the correct answer from the options given below:

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 from the options 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 options given below :