1
JEE Main 2023 (Online) 1st February Evening Shift
+4
-1

Which one of the following sets of ions represents a collection of isoelectronic species?

(Given : Atomic Number : $$\mathrm{F:9,Cl:17,Na=11,Mg=12,Al=13,K=19,Ca=20,Sc=21}$$)

A
$$\mathrm{N}^{3-}, \mathrm{O}^{2-}, \mathrm{F}^{-}, \mathrm{S}^{2-}$$
B
$$\mathrm{Ba}^{2+}, \mathrm{Sr}^{2+}, \mathrm{K}^{+}, \mathrm{Ca}^{2+}$$
C
$$\mathrm{Li}^{+}, \mathrm{Na}^{+}, \mathrm{Mg}^{2+}, \mathrm{Ca}^{2+}$$
D
$$\mathrm{K}^{+}, \mathrm{Cl}^{-}, \mathrm{Ca}^{2+}, \mathrm{Sc}^{3+}$$
2
JEE Main 2023 (Online) 31st January Evening Shift
+4
-1
Arrange the following orbitals in decreasing order of energy.

A. $\mathrm{n}=3, \mathrm{l}=0, \mathrm{~m}=0$

B. $\mathrm{n}=4, \mathrm{l}=0, \mathrm{~m}=0$

C. $\mathrm{n}=3, \mathrm{l}=1, \mathrm{~m}=0$

D. $\mathrm{n}=3, \mathrm{l}=2, \mathrm{~m}=1$

The correct option for the order is :
A
$\mathrm{B}>\mathrm{D}>\mathrm{C}>\mathrm{A}$
B
$\mathrm{A}>\mathrm{C}>\mathrm{B}>\mathrm{D}$
C
$\mathrm{D}>\mathrm{B}>\mathrm{A}>\mathrm{C}$
D
$\mathrm{D}>\mathrm{B}>\mathrm{C}>\mathrm{A}$
3
JEE Main 2023 (Online) 31st January Morning Shift
+4
-1

$$\mathrm{Nd^{2+}}$$ = __________

A
$$\mathrm{4f^4 6s^2}$$
B
$$\mathrm{4f^3}$$
C
$$\mathrm{4f^4}$$
D
$$\mathrm{4f^2 6s^2}$$
4
JEE Main 2023 (Online) 31st January Morning Shift
+4
-1

Which transition in the hydrogen spectrum would have the same wavelength as the Balmer type transition from $$\mathrm{n=4}$$ to $$\mathrm{n}=2$$ of $$\mathrm{He}^{+}$$ spectrum

A
$$\mathrm{n}=3$$ to $$\mathrm{n}=4$$
B
$$\mathrm{n}=2$$ to $$\mathrm{n}=1$$
C
$$\mathrm{n}=1$$ to $$\mathrm{n}=2$$
D
$$\mathrm{n}=1$$ to $$\mathrm{n}=3$$
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