d and f Block Elements · Chemistry · JEE Main

The correct decreasing order of spin only magnetic moment values (BM) of Cu⁺, Cu²⁺, Cr²⁺ and Cr³⁺ ions is :

The first transition series metal ' $M$ ' has the highest enthalpy of atomisation in its series. One of its aquated ion $\left(\mathrm{M}^{\mathrm{n}+}\right)$ exists in green colour. The nature of the oxide formed by the above $\mathrm{M}^{\mathrm{n}+}$ ion is:

Pair of transition metal ions having the same number of unpaired electrons is

Given below are two statements:

Statement I : $\mathrm{CrO}_3$ is a stronger oxidizing agent than $\mathrm{MoO}_3$

Statement II : $\mathrm{Cr}(\mathrm{VI})$ is more stable than $\mathrm{Mo}(\mathrm{VI})$

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

The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are :

A. $\mathrm{Cr}^{2+}$

B. $\mathrm{Fe}^{2+}$

C. $\mathrm{Fe}^{3+}$

D. $\mathrm{Co}^{2+}$

E. $\mathrm{Mn}^{3+}$

Choose the correct answer from the options given below:

The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :

The metal ion whose electronic configuration is not affected by the nature of the ligand and which gives a violet colour in non-luminous flame under hot condition in borax bead test is

Match List - I with List - II.

Choose the correct answer from the options given below :

Preparation of potassium permanganate from $\mathrm{MnO}_2$ involves two step process in which the 1st step is a reaction with KOH and $\mathrm{KNO}_3$ to produce

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

Match List - I with List - II

Choose the correct answer from the options given below :

Consider the following reactions

$$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7 \xrightarrow[-\mathrm{H}_2 \mathrm{O}]{\mathrm{KOH}}[\mathrm{~A}] \xrightarrow[-\mathrm{H}_2 \mathrm{O}]{\mathrm{H}_2 \mathrm{SO}_4}[\mathrm{~B}]+\mathrm{K}_2 \mathrm{SO}_4$$

The products $[A]$ and $[B]$, respectively are :

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

Lanthanoid ions with $4 \mathrm{f}^7$ configuration are :

(A) $\mathrm{Eu}^{2+}$

(B) $\mathrm{Gd}^{3+}$

(C) $\mathrm{Eu}^{3+}$

(D) $\mathrm{Tb}^{3+}$

(E) $ \mathrm{Sm}^{2+}$

Choose the correct answer from the options given below :

The electronic configuration of Einsteinium is :

(Given atomic number of Einsteinium $$=99$$)

Give below are two statements :

Statement I : The higher oxidation states are more stable down the group among transition elements unlike p-block elements.

Statement II : Copper can not liberate hydrogen from weak acids.

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

The electronic configuration of $$\mathrm{Cu}(\mathrm{II})$$ is $$3 \mathrm{~d}^9$$ whereas that of $$\mathrm{Cu}(\mathrm{I})$$ is $$3 \mathrm{~d}^{10}$$. Which of the following is correct?

Iron (III) catalyses the reaction between iodide and persulphate ions, in which

A. $$\mathrm{Fe}^{3+}$$ oxidises the iodide ion

B. $$\mathrm{Fe}^{3+}$$ oxidises the persulphate ion

C. $$\mathrm{Fe}^{2+}$$ reduces the iodide ion

D. $$\mathrm{Fe}^{2+}$$ reduces the persulphate ion

Choose the most appropriate answer from the options given below:

Arrange the following elements in the increasing order of number of unpaired electrons in it.

(A) $$\mathrm{Sc}$$

(B) $$\mathrm{Cr}$$

(C) $$\mathrm{V}$$

(D) $$\mathrm{Ti}$$

(E) $$\mathrm{Mn}$$

Choose the correct answer from the options given below :

The number of element from the following that do not belong to lanthanoids is $$\mathrm{Eu}, \mathrm{Cm}, \mathrm{Er}, \mathrm{Tb}, \mathrm{Yb}$$ and $$\mathrm{Lu}$$

While preparing crystals of Mohr's salt, dil $$\mathrm{H}_2 \mathrm{SO}_4$$ is added to a mixture of ferrous sulphate and ammonium sulphate, before dissolving this mixture in water, dil $$\mathrm{H_2SO_4}$$ is added here to :

The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is _________.

$$\mathrm{Ti}^{2+}, \mathrm{Cr}^{2+} \text { and } \mathrm{V}^{2+}$$

The metal that shows highest and maximum number of oxidation state is :

The element which shows only one oxidation state other than its elemental form is :

Choose the correct statements from the following

A. $$\mathrm{Mn}_2 \mathrm{O}_7$$ is an oil at room temperature

B. $$\mathrm{V}_2 \mathrm{O}_4$$ reacts with acid to give $$\mathrm{VO}_2{ }^{2+}$$

C. $$\mathrm{CrO}$$ is a basic oxide

D. $$\mathrm{V}_2 \mathrm{O}_5$$ does not react with acid

Choose the correct answer from the options given below :

Identify correct statements from below:

A. The chromate ion is square planar.

B. Dichromates are generally prepared from chromates.

C. The green manganate ion is diamagnetic.

D. Dark green coloured $$\mathrm{K}_2 \mathrm{MnO}_4$$ disproportionates in a neutral or acidic medium to give permanganate.

E. With increasing oxidation number of transition metal, ionic character of the oxides decreases.

Choose the correct answer from the options given below:

The metals that are employed in the battery industries are

A. $$\mathrm{Fe}$$

B. $$\mathrm{Mn}$$

C. $$\mathrm{Ni}$$

D. $$\mathrm{Cr}$$

E. $$\mathrm{Cd}$$

Choose the correct answer from the options given below:

The orange colour of $$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$$ and purple colour of $$\mathrm{KMnO}_4$$ is due to

Diamagnetic Lanthanoid ions are :

Which of the following acts as a strong reducing agent? (Atomic number: $$\mathrm{Ce}=58, \mathrm{Eu}=63, \mathrm{Gd}=64, \mathrm{Lu}=71$$)

Which of the following statements are correct about $$\mathrm{Zn}, \mathrm{Cd}$$ and $$\mathrm{Hg}$$ ?

A. They exhibit high enthalpy of atomization as the d-subshell is full.

B. $$\mathrm{Zn}$$ and $$\mathrm{Cd}$$ do not show variable oxidation state while $$\mathrm{Hg}$$ shows $$+\mathrm{I}$$ and $$+\mathrm{II}$$.

C. Compounds of $$\mathrm{Zn}, \mathrm{Cd}$$ and $$\mathrm{Hg}$$ are paramagnetic in nature.

D. $$\mathrm{Zn}, \mathrm{Cd}$$ and $$\mathrm{Hg}$$ are called soft metals.

Choose the most appropriate from the options given below:

The correct IUPAC name of $$\mathrm{K}_2 \mathrm{MnO}_4$$ is

$$\mathrm{KMnO}_4$$ decomposes on heating at $$513 \mathrm{~K}$$ to form $$\mathrm{O}_2$$ along with

Given below are two statements :

Statement (I) : In the Lanthanoids, the formation $$\mathrm{Ce}^{+4}$$ is favoured by its noble gas configuration.

Statement (II) : $$\mathrm{Ce}^{+4}$$ is a strong oxidant reverting to the common +3 state.

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

Choose the correct option having all the elements with $$\mathrm{d}^{10}$$ electronic configuration from the following :

Which of the following electronic configuration would be associated with the highest magnetic moment?

$$\mathrm{NaCl}$$ reacts with conc. $$\mathrm{H}_2 \mathrm{SO}_4$$ and $$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$$ to give reddish fumes (B), which react with $$\mathrm{NaOH}$$ to give yellow solution (C). (B) and (C) respectively are ;

The electronic configuration for Neodymium is:

[Atomic Number for Neodymium 60]

The pair of lanthanides in which both elements have high third - ionization energy is :

Given below are two statement: one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$

Assertion A: $$5 \mathrm{f}$$ electrons can participate in bonding to a far greater extent than $$4 \mathrm{f}$$ electrons

Reason R: $$5 \mathrm{f}$$ orbitals are not as buried as $$4 \mathrm{f}$$ orbitals

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

Prolonged heating is avoided during the preparation of ferrous ammonium sulphate to :

Which of the following statements are correct?

(A) The M$$^{3+}$$/M$$^{2+}$$ reduction potential for iron is greater than manganese.

(B) The higher oxidation states of first row d-block elements get stabilized by oxide ion.

(C) Aqueous solution of Cr$$^{2+}$$ can liberate hydrogen from dilute acid.

(D) Magnetic moment of V$$^{2+}$$ is observed between 4.4 - 5.2 BM.

Choose the correct answer from the options given below :

Which halogen is known to cause the reaction given below :

$$2 \mathrm{Cu}^{2+}+4 \mathrm{X}^{-} \rightarrow \mathrm{Cu}_{2} \mathrm{X}_{2}(\mathrm{s})+\mathrm{X}_{2}$$

In chromyl chloride, the number of d-electrons present on chromium is same as in

(Given at no. of $$\mathrm{Ti}: 22, \mathrm{~V}: 23, \mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26$$ )

Element not present in Nessler's reagent is :

Given below are two statements: one is labelled as "Assertion A" and the other is labelled as "Reason R"

Assertion A : In the complex $$\mathrm{Ni}(\mathrm{CO})_{4}$$ and $$\mathrm{Fe}(\mathrm{CO})_{5}$$, the metals have zero oxidation state.

Reason R : Low oxidation states are found when a complex has ligands capable of $$\pi$$-donor character in addition to the $\sigma$-bonding.

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

During the reaction of permanganate with thiosulphate, the change in oxidation of manganese occurs by value of 3. Identify which of the below medium will favour the reaction.

Strong reducing and oxidizing agents among the following, respectively, are :

Which element is not present in Nessler's reagent?

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : $$\mathrm{Cu^{2+}}$$ in water is more stable than $$\mathrm{Cu^{+}}$$.

Reason (R) : Enthalpy of hydration for $$\mathrm{Cu^{2+}}$$ is much less than that of $$\mathrm{Cu^{+}}$$.

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

Highest oxidation state of Mn is exhibited in $$\mathrm{Mn_2O_7}$$. The correct statements about $$\mathrm{Mn_2O_7}$$ are

(A) Mn is tetrahedrally surrounded by oxygen atoms.

(B) Mn is octahedrally surrounded by oxygen atoms.

(C) Contains Mn-O-Mn bridge.

(D) Contains Mn-Mn bond.

Choose the correct answer from the options given below :

When $$\mathrm{Cu}^{2+}$$ ion is treated with $$\mathrm{KI}$$, a white precipitate, $$\mathrm{X}$$ appears in solution. The solution is titrated with sodium thiosulphate, the compound $$\mathrm{Y}$$ is formed. $$\mathrm{X}$$ and $$\mathrm{Y}$$ respectively are :

$$\mathrm{Nd^{2+}}$$ = __________

The correct order of basicity of oxides of vanadium is :

During the qualitative analysis of $$\mathrm{SO}_{3}^{2-}$$ using dilute $$\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{SO}_{2}$$ gas is evolved which turns $$\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$$ solution (acidified with dilute $$\mathrm{H}_{2} \mathrm{SO}_{4}$$) :

Given below are two statements :

Statement I : Nickel is being used as the catalyst for producing syn gas and edible fats.

Statement II : Silicon forms both electron rich and electron deficient hydrides.

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

The set of correct statements is :

(i) Manganese exhibits +7 oxidation state in its oxide.

(ii) Ruthenium and Osmium exhibit +8 oxidation in their oxides.

(iii) Sc shows +4 oxidation state which is oxidizing in nature.

(iv) Cr shows oxidising nature in +6 oxidation state.

An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with $$\mathrm{H_2O_2}$$ at room temp. The indicator 'X' forms blue coloured complex with compound 'A' present in the solution. The indicator 'X' and compound 'A' respectively are :

A chloride salt solution acidified with dil.HNO$$_3$$ gives a curdy white precipitate, [A], on addition of AgNO$$_3$$. [A] on treatment with NH$$_4$$OH gives a clear solution B. A and B are respectively :

Which one amongst the following are good oxidizing agents?

A. Sm$$^{2+}$$

B. Ce$$^{2+}$$

C. Ce$$^{4+}$$

D. Tb$$^{4+}$$

Choose the most appropriate answer from the options given below :

An ammoniacal metal salt solution gives a brilliant red precipitate on addition of dimethylglyoxime. The metal ion is :

Which of the following $$3\mathrm{d}$$-metal ion will give the lowest enthalpy of hydration $$\left(\Delta_{\text {hyd }} \mathrm{H}\right)$$ when dissolved in water ?

The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives :

In following pairs, the one in which both transition metal ions are colourless is :

In neutral or faintly alkaline medium, $$\mathrm{KMnO}_{4}$$ being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be :

Match List - I with List - II, match the gas evolved during each reaction.

Choose the correct answer from the options given below :

Which of the following has least tendency to liberate $$\mathrm{H}_{2}$$ from mineral acids?

In neutral or alkaline solution, $$\mathrm{MnO}_{4}^{-}$$ oxidises thiosulphate to :

Given below are two statements.

Statement I : Iron (III) catalyst, acidified $$\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$$ and neutral $$\mathrm{KMnO}_{4}$$ have the ability to oxidise $$\mathrm{I}^{-}$$ to $$\mathrm{I}_{2}$$ independently.

Statement II : Manganate ion is paramagnetic in nature and involves $$\mathrm{p} \pi-\mathrm{p} \pi$$ bonding.

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

The total number of $$\mathrm{Mn}=\mathrm{O}$$ bonds in $$\mathrm{Mn}_{2} \mathrm{O}_{7}$$ is __________.

The dark purple colour of $$\mathrm{KMnO}_{4}$$ disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is :

The electronic configuration of Pt (atomic number 78) is :

Which one of the lanthanoids given below is the most stable in divalent form?

[Given : Atomic no. Eu, 63; Sm, 62; Tm, 69; Tb, 65; Yb, 70; Dy, 66]

The most common oxidation state of Lanthanoid elements is +3. Which of the following is likely to deviate easily from +3 oxidation state?

The metal ion (in gaseous state) with lowest spin-only magnetic moment value is :

Cerium (IV) has a noble gas configuration. Which of the following is correct statement about it?

Among the following, which is the strongest oxidizing agent?

Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be :

Consider the following reactions

$$ \begin{aligned} & \mathrm{A}+\underset{\substack{ \text { Little } \\ \text { amount }}}{\mathrm{NaCl}}+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{CrO}_2 \mathrm{Cl}_2+\text { Side Products } \\ & \mathrm{CrO}_2 \mathrm{Cl}_{2 \text { (Vapour) }}+\mathrm{NaOH} \rightarrow \mathrm{~B}+\mathrm{NaCl}+\mathrm{H}_2 \mathrm{O} \\ & \mathrm{~B}+\mathrm{H}^{+} \rightarrow \mathrm{C}+\mathrm{H}_2 \mathrm{O} \end{aligned} $$

The number of terminal ' $O$ ' present in the compound ' C ' is__________

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.

Niobium $(\mathrm{Nb})$ and ruthenium $(\mathrm{Ru})$ have " $x$ " and " $y$ " number of electrons in their respective 4 d orbitals. The value of $x+y$ is __________.

A transition metal '$$\mathrm{M}$$' among $$\mathrm{Sc}, \mathrm{Ti}, \mathrm{V}, \mathrm{Cr}, \mathrm{Mn}$$ and $$\mathrm{Fe}$$ has the highest second ionisation enthalpy. The spin-only magnetic moment value of $$\mathrm{M}^{+}$$ ion is _______ BM (Near integer)

(Given atomic number $$\mathrm{Sc}: 21, \mathrm{Ti}: 22, \mathrm{~V}: 23, \mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26$$)

Number of colourless lanthanoid ions among the following is __________.

$$\mathrm{Eu}^{3+}, \mathrm{Lu}^{3+}, \mathrm{Nd}^{3+}, \mathrm{La}^{3+}, \mathrm{Sm}^{3+}$$

Among $$\mathrm{VO}_2^{+}, \mathrm{MnO}_4^{-}$$ and $$\mathrm{Cr}_2 \mathrm{O}_7^{2-}$$, the spin-only magnetic moment value of the species with least oxidising ability is __________ BM (Nearest integer).

(Given atomic member $$\mathrm{V}=23, \mathrm{Mn}=25, \mathrm{Cr}=24$$)

Among $$\mathrm{CrO}, \mathrm{Cr}_2 \mathrm{O}_3$$ and $$\mathrm{CrO}_3$$, the sum of spin-only magnetic moment values of basic and amphoteric oxides is _________ $$10^{-2} \mathrm{BM}$$ (nearest integer).

(Given atomic number of $$\mathrm{Cr}$$ is 24 )

The fusion of chromite ore with sodium carbonate in the presence of air leads to the formation of products $$\mathrm{A}$$ and $$\mathrm{B}$$ along with the evolution of $$\mathrm{CO}_2$$. The sum of spin-only magnetic moment values of A and B is _________ B.M. (Nearest integer)

[Given atomic number : $$\mathrm{C}: 6, \mathrm{Na}: 11, \mathrm{O}: 8, \mathrm{Fe}: 26, \mathrm{Cr}: 24$$]

In a borax bead test under hot condition, a metal salt (one from the given) is heated at point B of the flame, resulted in green colour salt bead. The spin-only magnetic moment value of the salt is _______ BM (Nearest integer) [Given atomic number of $$\mathrm{Cu}=29, \mathrm{Ni}=28, \mathrm{Mn}=25, \mathrm{Fe}=26$$]

A first row transition metal with highest enthalpy of atomisation, upon reaction with oxygen at high temperature forms oxides of formula $$\mathrm{M}_2 \mathrm{O}_{\mathrm{n}}$$ (where $$\mathrm{n}=3,4,5$$). The 'spin-only' magnetic moment value of the amphoteric oxide from the above oxides is _________ $$\mathrm{BM}$$ (near integer)

(Given atomic number: $$\mathrm{Sc}: 21, \mathrm{Ti}: 22, \mathrm{~V}: 23, \mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26, \mathrm{Co}: 27, \mathrm{Ni}: 28, \mathrm{Cu}: 29, \mathrm{Zn}: 30$$)

Consider the following reaction

$$\mathrm{MnO}_2+\mathrm{KOH}+\mathrm{O}_2 \rightarrow \mathrm{A}+\mathrm{H}_2 \mathrm{O} \text {. }$$

Product '$$\mathrm{A}$$' in neutral or acidic medium disproportionate to give products '$$\mathrm{B}$$' and '$$\mathrm{C}$$' along with water. The sum of spin-only magnetic moment values of $$\mathrm{B}$$ and $$\mathrm{C}$$ is ________ BM. (nearest integer) (Given atomic number of $$\mathrm{Mn}$$ is 25)

Number of metal ions characterized by flame test among the following is ________.

$$\mathrm{Sr}^{2+}, \mathrm{Ba}^{2+}, \mathrm{Ca}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Zn}^{2+}, \mathrm{Co}^{2+}, \mathrm{Fe}^{2+}$$

Total number of ions from the following with noble gas configuration is _________.

$$\mathrm{Sr}^{2+}(z=38), \mathrm{Cs}^{+}(z=55), \mathrm{La}^{2+}(z=57), \mathrm{Pb}^{2+}(z=82), \mathrm{Yb}^{2+}(z=70)$$ and $$\mathrm{Fe}^{2+}(z=26)$$

Among following compounds, the number of those present in copper matte is ___________.

A. $$\mathrm{CuCO_{3}}$$

B. $$\mathrm{Cu_{2}S}$$

C. $$\mathrm{Cu_{2}O}$$

D. $$\mathrm{FeO}$$

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is _____________.

How many of the following metal ions have similar value of spin only magnetic moment in gaseous state? ______________

(Given : Atomic number V, 23; Cr, 24; Fe, 26; Ni, 28)

V$$^{3+}$$, Cr$$^{3+}$$, Fe$$^{2+}$$, Ni$$^{3+}$$

The disproportionation of $$\mathrm{MnO}_{4}^{2-}$$ in acidic medium resulted in the formation of two manganese compounds $$\mathrm{A}$$ and $$\mathrm{B}$$. If the oxidation state of $$\mathrm{Mn}$$ in $$\mathrm{B}$$ is smaller than that of A, then the spin-only magnetic moment $$(\mu)$$ value of B in BM is __________. (Nearest integer)

The spin-only magnetic moment value of the compound with strongest oxidizing ability among $$\mathrm{MnF}_{4}, \mathrm{MnF}_{3}$$ and $$\mathrm{MnF}_{2}$$ is ____________ B.M. [nearest integer]

Among Co³⁺, Ti²⁺, V²⁺ and Cr²⁺ ions, one if used as a reagent cannot liberate H₂ from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is ___________ B.M. (Nearest integer)

Spin only magnetic moment of [MnBr₆]^4$$-$$ is _________ B.M. (round off to the closest integer)

For the reaction given below :

CoCl₃ . xNH₃ + AgNO₃ (aq) $$\to$$

If two equivalents of AgCl precipitate out, then the value of x will be _____________.

The number of terminal oxygen atoms present in the product B obtained from the following reaction is _____________.

FeCr₂O₄ + Na₂CO₃ + O₂ $$\to$$ A + Fe₂O₃ + CO₂

A + H⁺ $$\to$$ B + H₂O + Na⁺

An acidified manganate solution undergoes disproportionation reaction. The spin-only magnetic moment value of the product having manganese in higher oxidation state is _____________ B.M. (Nearest integer)

The number of statements correct from the following for Copper (at. no. 29) is/are ____________.

(A) Cu(II) complexes are always paramagnetic.

(B) Cu(I) complexes are generally colourless

(C) Cu(I) is easily oxidized

(D) In Fehling solution, the active reagent has Cu(I)

The spin-only magnetic moment value of the most basic oxide of vanadium among V₂O₃, V₂O₄ and V₂O₅ is _____________ B.M. (Nearest integer)

Manganese (VI) has ability to disproportionate in acidic solution. The difference in oxidation states of two ions it forms in acidic solution is ____________.

The difference in oxidation state of chromium in chromate and dichromate salts is ___________.

Which of the following pair is not isoelectronic species?

(At. no. Sm, 62; Er, 68; Yb, 70; Lu, 71; Eu, 63; Tb, 65; Tm, 69)