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1

JEE Main 2021 (Online) 27th August Morning Shift

Numerical
The number of f electrons in the ground state electronic configuration of Np (Z = 93) is ___________. (Nearest integer)
Your Input ________

Answer

Correct Answer is 18

Explanation

Np = 1s2 22 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2

4f14 5d10 6p6 7s2 5f4 6d1

Total No. of 'f' electron = 14e$$-$$ + 4e$$-$$ = 18
2

JEE Main 2021 (Online) 26th August Morning Shift

Numerical
The number of 4f electrons in the ground statement electronic configuration of Gd2+ is ___________. [Atomic number of Gd = 64]
Your Input ________

Answer

Correct Answer is 7

Explanation

The electronic configuration of

$$_{64}Gd:[Xe]4{f^7}5{d^1}6{s^2}$$

So, the electronic configuration of

$$_{64}G{d^{2 + }}:[Xe]4{f^7}5{d^1}6{s^0}$$

i.e. the number of 4f electrons in the ground state electronic configuration of $$G{d^{2 + }}$$ is 7.
3

JEE Main 2021 (Online) 26th August Morning Shift

Numerical
These are physical properties of an element

(A) Sublimation enthalpy

(B) Ionisation enthalpy

(C) Hydration enthalpy

(D) Electron gain enthalpy

The total number of above properties that affect the reduction potential is ____________ (Integer answer)
Your Input ________

Answer

Correct Answer is 3

Explanation

Sublimation enthalpy, Ionisation enthalpy and hydration enthalpy affect the reduction potential.
4

JEE Main 2021 (Online) 25th July Evening Shift

Numerical
Number of electrons present in 4f orbital of Ho3+ ion is ____________. (Given Atomic No. of Ho = 67)
Your Input ________

Answer

Correct Answer is 10

Explanation

Ho = [Xe]4f116s2

Ho3+ = [Xe] 4f10

So number of e$$-$$ present in 4f is 10.

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