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

Q 31 :

The magnetic moment of transition metal compound has been calculated to be 3.87 B.M. The metal ion is [2023]

${Ti}^{2 +}$
${Mn}^{2 +}$
$V^{2 +}$
${Cr}^{2 +}$

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Ion	Outer electronic configuration	No. of unpaired electrons	Magnetic moment
${Mn}^{2 +}$	$3 d^{5} 4 s^{0}$	5	$\sqrt{35} BM$
$V^{2 +}$	$3 d^{3} 4 s^{0}$	3	$\sqrt{15} BM$
${Ti}^{2 +}$	$3 d^{2} 4 s^{0}$	2	$\sqrt{8} BM$
${Cr}^{2 +}$	$3 d^{4} 4 s^{0}$	4	$\sqrt{24} BM$

Q 32 :

The set of correct statements is: [2023]

(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.

(i) and (iii)
(ii) and (iii)
(i), (ii) and (iv)
(ii), (iii) and (iv)

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(3)

${}_{21}{Sc} = 3 d^{1} 4 s^{2}$ can show maximum +3 oxidation state but does not show +4 oxidation state.

Q 33 :

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: [2023]

Statement I is incorrect but statement II is correct.
Both the statements I and II are correct.
Statement I is correct but statement II is incorrect.
Both the statement I and II are incorrect.

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${CH}_{4}$ $(g)$ $+ H_{2} O$ $(g)$ $\to_{Ni}^{1270 K} CO$ $(g)$ $+ 3 H_{2}$ $(g)$

Hydrogenation of vegetable oils using Ni catalyst gives edible fats.

$C$ $(s)$ $+ H_{2} O$ $(g)$ $\overset{1270 K}{\to} CO$ $(g)$ $+ H_{2}$ $(g)$
(coal gasification)

Q 34 :

Highest oxidation state of Mn is exhibited in ${Mn}_{2} O_{7}$ . The correct statements about ${Mn}_{2} O_{7}$ 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: [2023]

A and D only
A and C only
B and C only
B and D only

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(2)

${Mn}_{2} O_{7}$

[IMAGE 155]

Q 35 :

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

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

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

In the light of the above statements, choose the correct answer from the options given below: [2023]

Both (A) and (R) are correct and (R) is the correct explanation of (A)
(A) is correct but (R) is not correct
Both (A) and (R) are correct but (R) is not the correct explanation of (A)
(A) is not correct but (R) is correct

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(2)

In aqueous solution, ${Cu}^{+ 1}$ is unstable and it disproportionates.

$2 {Cu}^{+ 1} ⟶ Cu (s) + {Cu}^{+ 2} (a q)$

Hydration energy of ${Cu}^{2 +}$ is higher than ${Cu}^{+ 1}$ and this compensates its ionisation energy.

Q 36 :

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 solutions of ${Cr}^{2 +}$ can liberate hydrogen from dilute acid.

(D) Magnetic moment of $V^{2 +}$ is observed between 4.4 – 5.2 B.M.

Choose the correct answer from the options given below: [2023]

(A), (B) only
(C), (D) only
(A), (B), (D) only
(B), (C) only

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

$E_{{Mn}^{3 +} / {Mn}^{2 +}}^{\circ} = + 1.57 V$

$E_{{Fe}^{3 +} / {Fe}^{2 +}}^{\circ} = + 0.77 V$

(B) ${CrO}_{4}^{- 2}, {MnO}_{4}^{-}$

(C) ${Cr}^{2 +} (aq) + H^{+} (aq) \to {Cr}^{3 +} (aq) + \frac{1}{2} H_{2} ↑$

(D) $V^{2 +}$ has three unpaired electrons therefore magnetic moment is 3.87 BM.

Q 37 :

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)

$V^{3 +}$ , ${Cr}^{3 +}$ , ${Fe}^{2 +}$ , ${Ni}^{3 +}$ [2023]

0%

(2)

[IMAGE 156]

Q 38 :

In ammonium–phosphomolybdate, the oxidation state of Mo is + ________. [2023]

0%

(6)

The oxidation state of Mo in ammonium phosphomolybdate = +6

${({NH}_{4})}_{3} {PO}_{4} . 12 {MoO}_{3}$

Q 39 :

For a metal ion, the calculated magnetic moment is 4.90 BM. This metal ion has ________ number of unpaired electrons. [2023]

0%

(4)

We have, $\sqrt{n (n + 2)} = 4.9 B.M$

$n (n + 2) = 24$

$n^{2} + 2 n - 24 = 0$

$n^{2} + 6 n - 4 n - 24 = 0$

$n (n + 6) - 4 (n + 6) = 0$

$∴$ $n = 4$

where $n =$ number of unpaired electrons.

Topic Question Set

Q 31 :

The magnetic moment of transition metal compound has been calculated to be 3.87 B.M. The metal ion is [2023]

Q 32 :

The set of correct statements is: [2023]

(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.

Q 37 :

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)

$V^{3 +}$ , ${Cr}^{3 +}$ , ${Fe}^{2 +}$ , ${Ni}^{3 +}$ [2023]

0%

Q 38 :

In ammonium–phosphomolybdate, the oxidation state of Mo is + ________. [2023]

0%

Q 39 :

For a metal ion, the calculated magnetic moment is 4.90 BM. This metal ion has ________ number of unpaired electrons. [2023]

0%

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