1

### NEET 2021

A particular station of All India Radio, New Delhi broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light c = 3.0 $\times$ 108 ms$-$1]
A
21.92 cm
B
219.3 m
C
219.2 m
D
2192 m

## Explanation

$= {{hc} \over \lambda } = h\gamma$

So, ${c \over \lambda } = \gamma$

$\Rightarrow \lambda = {c \over \gamma }$

$\lambda = {{3 \times {{10}^8}} \over {1368 \times {{10}^3}}} = 219.3$ m
2

### NEET 2019

4d, 5p, 5f and 6p orbitals are arranged in the order of decreasing energy. The correct option is :
A
6p > 5f > 4d > 5p
B
5f > 6p > 4d > 5p
C
5f > 6p > 5p > 4d
D
6p > 5f > 5p > 4d

## Explanation

As per Aufbau principle (n + l rule), higher is the value of (n + l), greater will be the energy. When (n + l) values are same then which orbital have higher value of n will have more energy.
4d = 4 + 2 = 6
5p = 5 + 1 = 6
5f = 5 + 3 = 8
6p = 6 + 1 = 7
Hence, the correct order of decreasing energy will
be : 5f > 6p > 5p > 4d.
3

### NEET 2019

Which of the following series of transitions in the spectrum of hydrogen atom falls in visible region?
A
Paschen series
B
Brackett series
C
Lyman series
D
Balmer series

## Explanation

Balmer series lies in visible region.
Paschen series lies in infra red region.
Brackett series lies in infra red region.
Lyman series lies in ultraviolet region.
4

### NEET 2018

Which one is a wrong statement?
A
Total orbital angular momentum of electron in s-orbital is equal to zero.
B
An orbital is designated by three quantum numbers while an electron in an atom is designated by four quantum numbers
C
The electronic configuration of N atom is
D
The value of m for dz2 is zero.

## Explanation

In degnerate orbital all unpaired electrons show same spin. So the correct configuration of N atom is