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

2024 12 questions

1. Q842024 · 9 Apr 2024 · Shift 1· Numerical answer

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

   Show answer

   Answer: 2

2. Q662024 · 9 Apr 2024 · Shift 2

   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
   Show answer

   Answer: C

3. Q892024 · 8 Apr 2024 · Shift 1· Numerical answer

   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: $\mathrm{Sc}=21,\mathrm{Ti}=22,\mathrm{V}=23,\mathrm{Cr}=24,\mathrm{Mn}=25\text{ and }\mathrm{Zn}=30$)

   Show answer

   Answer: 0

4. Q882024 · 6 Apr 2024 · Shift 2· Numerical answer

   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 $\text{V}=23,\text{Mn}=25,\text{Cr}=24$)

   Show answer

   Answer: 0

5. Q672024 · 4 Apr 2024 · Shift 1

   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
   Show answer

   Answer: A

6. Q752024 · 4 Apr 2024 · Shift 2

   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
   Show answer

   Answer: B

7. Q902024 · 4 Apr 2024 · Shift 2· Numerical answer

   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: $\text{Sc}:21,\text{Ti}:22,\text{V}:23,\text{Cr}:24,\text{Mn}:25,\text{Fe}:26,\text{Co}:27,\text{Ni}:28,\text{Cu}:29,\text{Zn}:30$)

   Show answer

   Answer: 0

8. Q772024 · 1 Feb 2024 · Shift 1

   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 $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$
   Show answer

   Answer: B

9. Q742024 · 31 Jan 2024 · Shift 1

   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
   Show answer

   Answer: A

10. Q852024 · 31 Jan 2024 · Shift 1· Numerical answer

    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 $\mathrm{Ni}:28$)

    Show answer

    Answer: 28

11. Q842024 · 31 Jan 2024 · Shift 2· Numerical answer

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

    Show answer

    Answer: 6

12. Q722024 · 27 Jan 2024 · Shift 2

    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.
    Show answer

    Answer: C