d- and f-Block Elements · JEE Main previous year questions

What volume of hydrogen gas at STP would be liberated by action of $50\mathrm{mL}$ of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ of $50\%$ purity ($\text{density}=1.3\mathrm{g}\mathrm{m}{\mathrm{L}}^{-1}$) on $20\mathrm{g}$ of zinc ? Given : Molar mass of $\mathrm{H}$, $\mathrm{O}$, $\mathrm{S}$, $\mathrm{Zn}$ are $1$, $16$, $32$, $65\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ respectively.

1. A.$5.824\mathrm{L}$
2. B.$7.428\mathrm{L}$
3. C.$6.892\mathrm{L}$
4. D.$8.375\mathrm{L}$

The correct statements among the following are, A. $\mathrm{Mo}(\mathrm{VI})$ and $\mathrm{W}(\mathrm{VI})$ are less stable than $\mathrm{Cr}(\mathrm{VI})$. B. $\mathrm{C}{\mathrm{e}}^{4+}$ and $\mathrm{T}{\mathrm{b}}^{4+}$ are oxidant while $\mathrm{E}{\mathrm{u}}^{2+}$ and $\mathrm{Y}{\mathrm{b}}^{2+}$ 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 options given below:

1. A.A and B Only
2. B.C and D Only
3. C.B and D Only
4. D.A and C Only

The mass of iron converted into $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4$ by the action of $18\mathrm{g}$ of steam is : (Given : Molar mass of H, O and Fe are 1, 16 and $56\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ respectively) Assume iron is present in excess :

1. A.$2.1\mathrm{g}$
2. B.$4.2\mathrm{g}$
3. C.$21\mathrm{g}$
4. D.$42\mathrm{g}$

1. A.
2. B.
3. C.
4. D.

The correct decreasing order of spin only magnetic moment values (BM) of $\mathrm{C}{\mathrm{u}}^{+}$, $\mathrm{C}{\mathrm{u}}^{2+}$, $\mathrm{C}{\mathrm{r}}^{2+}$ and $\mathrm{C}{\mathrm{r}}^{3+}$ ions is :

1. A.$\mathrm{C}{\mathrm{r}}^{3+}>\mathrm{C}{\mathrm{r}}^{2+}>\mathrm{C}{\mathrm{u}}^{+}>\mathrm{C}{\mathrm{u}}^{2+}$
2. B.$\mathrm{C}{\mathrm{u}}^{+}>\mathrm{C}{\mathrm{u}}^{2+}>\mathrm{C}{\mathrm{r}}^{3+}>\mathrm{C}{\mathrm{r}}^{2+}$
3. C.$\mathrm{C}{\mathrm{r}}^{2+}>\mathrm{C}{\mathrm{r}}^{3+}>\mathrm{C}{\mathrm{u}}^{2+}>\mathrm{C}{\mathrm{u}}^{+}$
4. D.$\mathrm{C}{\mathrm{u}}^{2+}>\mathrm{C}{\mathrm{u}}^{+}>\mathrm{C}{\mathrm{r}}^{2+}>\mathrm{C}{\mathrm{r}}^{3+}$

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

1. A.$\mathrm{T}{\mathrm{i}}^{3+},\mathrm{M}{\mathrm{n}}^{2+}$
2. B.$\mathrm{T}{\mathrm{i}}^{2+},\mathrm{C}{\mathrm{o}}^{2+}$
3. C.$\mathrm{F}{\mathrm{e}}^{3+},\mathrm{C}{\mathrm{r}}^{2+}$
4. D.${\mathrm{V}}^{2+},\mathrm{C}{\mathrm{o}}^{2+}$

Fortification of food with iron is done using $\mathrm{FeS}{\mathrm{O}}_4\cdot 7{\mathrm{H}}_2\mathrm{O}$. The mass in grams of the $\mathrm{FeS}{\mathrm{O}}_4\cdot 7{\mathrm{H}}_2\mathrm{O}$ required to achieve 12 ppm of iron in 150 kg of wheat is ____ (Nearest integer) [Given: Molar mass of Fe, S and O respectively are 56, 32 and $16\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ ]

The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are : A. $\mathrm{C}{\mathrm{r}}^{2+}$ B. $\mathrm{F}{\mathrm{e}}^{2+}$ C. $\mathrm{F}{\mathrm{e}}^{3+}$ D. $\mathrm{C}{\mathrm{o}}^{2+}$ E. $\mathrm{M}{\mathrm{n}}^{3+}$ Choose the correct answer from the options given below:

1. A.A, D and E Only
2. B.A, B and E Only
3. C.A, C and E Only
4. D.B and E Only

Among, $\mathrm{Sc},\mathrm{Mn},\mathrm{Co}$ and $\mathrm{Cu}$, identify the element with highest enthalpy of atomisation. The spin only magnetic moment value of that element in its $+2$ oxidation state is__________$\mathrm{BM}$ (in nearest integer).

The calculated spin-only magnetic moments of ${\mathrm{K}}_3[\mathrm{Fe}(\mathrm{OH}{)}_6]$ and ${\mathrm{K}}_4[\mathrm{Fe}(\mathrm{OH}{)}_6]$ respectively are :

1. A.$4.90$ and $4.90B.M.$
2. B.$4.90$ and $5.92B.M.$
3. C.$5.92$ and $4.90B.M.$
4. D.$3.87$ and $4.90B.M.$

Which of the following oxidation reactions are carried out by both ${\mathrm{K}}_2\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7$ and $\mathrm{KMn}{\mathrm{O}}_4$ in acidic medium? A. ${\mathrm{I}}^{-}\to {\mathrm{I}}_2$ B. ${\mathrm{S}}^{2-}\to \mathrm{S}$ C. $\mathrm{F}{\mathrm{e}}^{2+}\to \mathrm{F}{\mathrm{e}}^{3+}$ D. ${\mathrm{I}}^{-}\to \mathrm{I}{\mathrm{O}}_3^{-}$ E. ${\mathrm{S}}_2{\mathrm{O}}_3^{2-}\to \mathrm{S}{\mathrm{O}}_4^{2-}$ Choose the correct answer from the options given below :

1. A.A, B and C Only
2. B.C, D and E Only
3. C.B, C and D Only
4. D.A, D and E Only

Match List - I with List - II. | List - I (Transition metal ion) | List - II (Spin only magnetic moment (B.M.)) | | :--- | :--- | | (A) ${\mathrm{Ti}}^{3+}$ | (I) 3.87 | | (B) ${\mathrm{V}}^{2+}$ | (II) 0.00 | | (C) ${\mathrm{Ni}}^{2+}$ | (III) 1.73 | | (D) ${\mathrm{Sc}}^{3+}$ | (IV) 2.84 | Choose the correct answer from the options given below :

1. A.(A) – (III), (B) – (I), (C) – (IV), (D) – (II)
2. B.(A) – (II), (B) – (IV), (C) – (I), (D) – (III)
3. C.(A) – (III), (B) – (I), (C) – (II), (D) – (IV)
4. D.(A) – (IV), (B) – (II), (C) – (III), (D) – (I)

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 :

1. A.(B) and (E) only
2. B.(B) and (C) only
3. C.(A) and (D) only
4. D.(A) and (B) only

Number of colourless lanthanoid ions among the following is ____. $\mathrm{E}{\mathrm{u}}^{3+},\mathrm{L}{\mathrm{u}}^{3+},\mathrm{N}{\mathrm{d}}^{3+},\mathrm{L}{\mathrm{a}}^{3+},\mathrm{S}{\mathrm{m}}^{3+}$

Given 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 :

1. A.Statement I is true but Statement II is false
2. B.Both Statement I and Statement II are false
3. C.Both Statement I and Statement II are true
4. D.Statement I is false but Statement II is true

The 'spin only' magnetic moment value of $\mathrm{M}{\mathrm{O}}_4^{2-}$ is ____ $\mathrm{BM}$. (Where $\mathrm{M}$ is a metal having least metallic radii among $\mathrm{Sc},\mathrm{Ti},\mathrm{V},\mathrm{Cr},\mathrm{Mn}$ and $\mathrm{Zn}$ ). (Given atomic number: $\mathrm{Sc}=21,\mathrm{Ti}=22,\mathrm{V}=23,\mathrm{Cr}=24,\mathrm{Mn}=25\text{ and }\mathrm{Zn}=30$)

Among ${\text{VO}}_2^{+},{\text{MnO}}_4^{-}$ and ${\text{Cr}}_2{\text{O}}_7^{2-}$, the spin-only magnetic moment value of the species with least oxidising ability is ________ $\text{BM}$ (Nearest integer). (Given atomic member $\text{V}=23,\text{Mn}=25,\text{Cr}=24$)

In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to :

1. A.decrease concentration of ${}^{-}\mathrm{OH}$ ions
2. B.increase concentration of ${\mathrm{Cl}}^{-}$ ions
3. C.prevent interference by phosphate ions
4. D.increase concentration of ${\mathrm{N}{\mathrm{H}}_4}^{+}$ ions

A first row transition metal in its +2 oxidation state has a spin-only magnetic moment value of $3.86\text{ BM}$. The atomic number of the metal is

1. A.22
2. B.23
3. C.26
4. D.25

A first row transition metal with highest enthalpy of atomisation, upon reaction with oxygen at high temperature forms oxides of formula ${\text{M}}_2{\text{O}}_n$ (where $n=3,4,5$). The 'spin-only' magnetic moment value of the amphoteric oxide from the above oxides is ________ BM (near integer) (Given atomic number: $\text{Sc}:21,\text{Ti}:22,\text{V}:23,\text{Cr}:24,\text{Mn}:25,\text{Fe}:26,\text{Co}:27,\text{Ni}:28,\text{Cu}:29,\text{Zn}:30$)

In acidic medium, ${\mathrm{K}}_2\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7$ shows oxidising action as represented in the half reaction: $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7{}^{2-}+\mathrm{X}{\mathrm{H}}^{+}+\mathrm{Y}{\mathrm{e}}^{\ominus }\to 2\mathrm{A}+\mathrm{Z}{\mathrm{H}}_2\mathrm{O}$ $\mathrm{X},\mathrm{Y},\mathrm{Z}$ and $\mathrm{A}$ are respectively :

1. A.$14,7,6$ and $\mathrm{C}{\mathrm{r}}^{3+}$
2. B.$14,6,7$ and $\mathrm{C}{\mathrm{r}}^{3+}$
3. C.$8,4,6$ and $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$
4. D.$8,6,4$ and $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$

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 ${\mathrm{K}}_2\mathrm{Mn}{\mathrm{O}}_4$ 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:

1. A.B, D, E only
2. B.A, B, C only
3. C.A, D, E only
4. D.B, C, D only

The 'Spin only' Magnetic moment for $[\mathrm{Ni}(\mathrm{N}{\mathrm{H}}_3{)}_6{]}^{2+}$ is ____ $\times 10^{-1}\mathrm{BM}$. (given $=$ Atomic number of $\mathrm{Ni}:28$)

In the reaction of potassium dichromate, potassium chloride and sulfuric acid (conc.), the oxidation state of the chromium in the product is $(+)$ ____.

Which of the following statements is not correct about rusting of iron?

1. A.Rusting of iron is envisaged as setting up of electrochemical cell on the surface of iron object.
2. B.Dissolved acidic oxides ${\text{SO}}_2,{\text{NO}}_2$ in water act as catalyst in the process of rusting.
3. C.Coating of iron surface by tin prevents rusting, even if the tin coating is peeling off.
4. D.When $\text{pH}$ lies above 9 or 10, rusting of iron does not take place.