jee main chemistry important questions | d And f-Block Elements jee main questions FREE

Q 11 :
The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is ___________ .

${Ti}^{2 +}, {Cr}^{2 +}$ and $V^{2 +}$ . [2024]

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(A)

$M^{2 +}$ $\to$ $M^{3 +} + e^{-}$ $E_{M^{3 +} / M^{2 +}}^{°}$

$H^{+} + e^{-}$ $\to$ $\frac{1}{2} H_{2}$ $E_{H^{+} / H_{2}}^{°}$

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$M^{2 +} + H^{+}$ $\to$ $M^{3 +} + \frac{1}{2} H_{2}$ $E_{reaction}^{°} = E_{H^{+} / H_{2}}^{°} - E_{M^{3 +} / M^{2 +}}^{°}$

If $M^{2 +}$ liberates hydrogen from dilute acid, then:

$E_{r e a c t i o n}^{°} = E_{H^{+} / H_{2}}^{\circ} - E_{M^{3 +} / M^{2 +}}^{\circ} > 0$

$0 - E_{M^{3 +} / M^{2 +}}^{\circ} > 0$

$E_{M^{3 +} / M^{2 +}}^{\circ} < 0$

$As E_{{Ti}^{3 +} / {Ti}^{2 +}}^{\circ} = - 0.37 V, E_{V^{3 +} / V^{2 +}}^{\circ} = - 0.26 V, E_{{Cr}^{3 +} / {Cr}^{2 +}}^{\circ} = - 0.41 V$

${Ti}^{2 +}, V^{2 +} {and Cr}^{2 +}$ can liberate hydrogen from dilute acids.

Q 12 :
Arrange the following elements in the increasing order of the number of unpaired electrons in it.

(A) Sc (B) Cr (C) V (D) Ti (E) Mn

Choose the correct answer from the options given below: [2024]

(A) < (D) < (C) < (B) < (E)
(B) < (C) < (D) < (E) < (A)
(A) < (D) < (C) < (E) < (B)
(C) < (E) < (B) < (A) < (D)

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(C)

Element and electronic configuration	Number of unpaired electrons
(A) ${}_{21}{Sc} = {}_{18}{[Ar]} 3 d^{1} 4 s^{2}$	1
(B) ${}_{24}{Cr} = {}_{18}{[Ar]} 3 d^{5} 4 s^{1}$	6
(C) ${}_{23}V = {}_{18}{[Ar]} 3 d^{3} 4 s^{2}$	3
(D) ${}_{22}{Ti} = {}_{18}{[Ar]} 3 d^{2} 4 s^{2}$	2
(E) ${}_{25}{Mn} = {}_{18}{[Ar]} 3 d^{5} 4 s^{2}$	5

Q 13 :
The electronic configuration of Cu(II) is $3 d^{9}$ whereas that of Cu(I) is $3 d^{10}$ . Which of the following is correct? [2024]

Cu(I) and Cu(II) are equally stable
Cu(II) is less stable
Cu(II) is more stable
Stability of Cu(I) and Cu(II) depends on nature of copper salts.

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(C)

The stability of ${Cu}^{2 +}$ (aq) rather than ${Cu}^{+}$ (aq) is due to the much more negative $∆ H_{hyd}$ of ${Cu}^{2 +}$ (aq) than ${Cu}^{+}$ (aq), which more than compensates for the second ionisation enthalpy of Cu.

Q 14 :
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: [2024]

Statement I is true but Statement II is false
Both Statement I and Statement II are true
Statement I is false but Statement II is true
Both Statement I and Statement II are false

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(B)

Statement I: In d block elements stability of higher oxidation state increases down the group. For example, in group 6, Mo(VI) and W(VI) are found to be more stable than Cr(VI). Thus Cr(VI) in the form of dichromate in acidic medium is a strong oxidising agent, whereas ${MoO}_{3}$ and ${WO}_{3}$ are not. In p block elements, stability of lower oxidation state increases down the group due to inert pair effect.

Statement II: $E_{{Cu}^{2 +} / Cu}^{\circ} = + 0.34 V, E_{H^{+} / H_{2}}^{\circ} = 0 V$

For the reaction: $Cu + 2 H^{+} \to {Cu}^{2 +} + H_{2}$

$E_{reaction}^{\circ} = E_{H^{+} / H_{2}}^{\circ} - E_{{Cu}^{2 +} / Cu}^{\circ} = 0 V - 0.34 V = - 0.34 V$

Since potential of the reaction is negative copper cannot liberate hydrogen from dilute acids.

Q 15 :
The spin-only magnetic moment value of the ion among ${Ti}^{2 +}, V^{2 +}, {Co}^{3 +}$ and ${Cr}^{2 +}$ , that acts as strong oxidising agent in aqueous solution is _______ B.M. (Near integer).

(Given atomic numbers : Ti : 22, V : 23, Cr : 24, Co : 27) [2024]

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(5)

$E_{{Co}^{3 +} / {Co}^{2 +}}^{\circ} = + 1.97 V$

Since $E_{{Co}^{3 +} / {Co}^{2 +}}^{\circ} > 0, {Co}^{3 +}$ is a strong oxidizing agent.

${Co}^{3 +} = {}_{18} [Ar] 3 d^{6}$

Number of unpaired electrons in ${Co}^{3 +} (n) = 4$

Spin only magnetic moment $(μ)$

$= \sqrt{n (n + 2)} BM = \sqrt{4 (4 + 2)} BM = 4.9 BM \approx 5 BM$

Q 16 :
Total number of ions from the following with noble gas configuration is _______ .

${Sr}^{2 +} (z = 38), {Cs}^{+} (z = 55), {La}^{2 +} (z = 57), {Pb}^{2 +} (z = 82), {Yb}^{2 +} (z = 70)$ and ${Fe}^{2 +} (z = 26)$ [2024]

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(2)

Ion	Electronic configuration
${}_{38}{Sr}^{2 +}$	${}_{36}{[Kr]} 5 s^{0}$ (noble gas)
${}_{55}{Cs}^{+}$	${}_{54}{[Xe]} 6 s^{0}$ (noble gas)
${}_{57}{La}^{2 +}$	${}_{54}{[Xe]} 5 d^{1}$
${}_{82}{Pb}^{2 +}$	${}_{54}{[Xe]} 4 f^{14} 5 d^{10} 6 s^{2}$
${}_{70}{Yb}^{2 +}$	${}_{54}{[Xe]} 4 f^{14}$
${}_{26}{Fe}^{2 +}$	${}_{18}{[Ar]} 3 d^{6}$

Q 17 :
A transition metal ‘M’ among Sc, Ti, V, Cr, Mn and Fe has the highest second ionisation enthalpy. The spin-only magnetic moment value of $M^{+}$ ion is ______. B.M. (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26) [2024]

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(6)

Second ionization energy increases from left to right in periodic table.

Metal	Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn
Second ionization energy (kJ/mol)	1235	1309	1414	1592	1509	1561	1644	1752	1958	1734

Cr has more second ionization energy than Mn and Fe because the electron is removed from stable $d^{5}$ configuration.

${}_{24}{Cr} ({}_{18}{[Ar]} 3 d^{5} 4 s^{1}) \overset{{IE}_{1}}{\to} {Cr}^{+} ({}_{18}{[Ar]} 3 d^{5}) \overset{{IE}_{2}}{\to} {Cr}^{2 +} ({}_{18}{[Ar]} 3 d^{4})$

Thus the metal M is Cr. Number of unpaired electrons in ${Cr}^{+} (n)$ = 5.

Spin only magnetic moment

$(μ) = \sqrt{n (n + 2)} BM = \sqrt{5 (5 + 2)} BM = 5.92 BM$

Topic Question Set

Q 11 :
The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is ___________ .

${Ti}^{2 +}, {Cr}^{2 +}$ and $V^{2 +}$ . [2024]

Q 12 :
Arrange the following elements in the increasing order of the number of unpaired electrons in it.

(A) Sc (B) Cr (C) V (D) Ti (E) Mn

Choose the correct answer from the options given below: [2024]

Q 13 :
The electronic configuration of Cu(II) is $3 d^{9}$ whereas that of Cu(I) is $3 d^{10}$ . Which of the following is correct? [2024]

Q 15 :
The spin-only magnetic moment value of the ion among ${Ti}^{2 +}, V^{2 +}, {Co}^{3 +}$ and ${Cr}^{2 +}$ , that acts as strong oxidising agent in aqueous solution is _______ B.M. (Near integer).

(Given atomic numbers : Ti : 22, V : 23, Cr : 24, Co : 27) [2024]

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Q 16 :
Total number of ions from the following with noble gas configuration is _______ .

${Sr}^{2 +} (z = 38), {Cs}^{+} (z = 55), {La}^{2 +} (z = 57), {Pb}^{2 +} (z = 82), {Yb}^{2 +} (z = 70)$ and ${Fe}^{2 +} (z = 26)$ [2024]

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Q 17 :
A transition metal ‘M’ among Sc, Ti, V, Cr, Mn and Fe has the highest second ionisation enthalpy. The spin-only magnetic moment value of $M^{+}$ ion is ______. B.M. (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26) [2024]

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Topic Question Set

Q 11 : The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is ___________ . Ti2+,Cr2+ and V2+. [2024]

Q 12 : Arrange the following elements in the increasing order of the number of unpaired electrons in it. (A) Sc (B) Cr (C) V (D) Ti (E) Mn Choose the correct answer from the options given below: [2024]

Q 13 : The electronic configuration of Cu(II) is 3d9 whereas that of Cu(I) is 3d10. Which of the following is correct? [2024]

Q 15 : The spin-only magnetic moment value of the ion among Ti2+,V2+,Co3+ and Cr2+, that acts as strong oxidising agent in aqueous solution is _______ B.M. (Near integer). (Given atomic numbers : Ti : 22, V : 23, Cr : 24, Co : 27) [2024]

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Q 16 : Total number of ions from the following with noble gas configuration is _______ . Sr2+(z=38), Cs+(z=55), La2+(z=57), Pb2+(z=82), Yb2+(z=70) and Fe2+(z=26) [2024]

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Q 17 : A transition metal ‘M’ among Sc, Ti, V, Cr, Mn and Fe has the highest second ionisation enthalpy. The spin-only magnetic moment value of M+ ion is ______. B.M. (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26) [2024]

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Q 11 :
The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is ___________ .

${Ti}^{2 +}, {Cr}^{2 +}$ and $V^{2 +}$ . [2024]

Q 12 :
Arrange the following elements in the increasing order of the number of unpaired electrons in it.

(A) Sc (B) Cr (C) V (D) Ti (E) Mn

Choose the correct answer from the options given below: [2024]

Q 13 :
The electronic configuration of Cu(II) is $3 d^{9}$ whereas that of Cu(I) is $3 d^{10}$ . Which of the following is correct? [2024]

Q 15 :
The spin-only magnetic moment value of the ion among ${Ti}^{2 +}, V^{2 +}, {Co}^{3 +}$ and ${Cr}^{2 +}$ , that acts as strong oxidising agent in aqueous solution is _______ B.M. (Near integer).

(Given atomic numbers : Ti : 22, V : 23, Cr : 24, Co : 27) [2024]

Q 16 :
Total number of ions from the following with noble gas configuration is _______ .

${Sr}^{2 +} (z = 38), {Cs}^{+} (z = 55), {La}^{2 +} (z = 57), {Pb}^{2 +} (z = 82), {Yb}^{2 +} (z = 70)$ and ${Fe}^{2 +} (z = 26)$ [2024]

Q 17 :
A transition metal ‘M’ among Sc, Ti, V, Cr, Mn and Fe has the highest second ionisation enthalpy. The spin-only magnetic moment value of $M^{+}$ ion is ______. B.M. (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26) [2024]