Structure of Atom — Page 2 | NEET Chemistry

Q11

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

10 8 ms

-

1 ]

A 21.92 cm

B 219.3 m

C 219.2 m

D 2192 m

Correct Answer

Option B

Solution

Energy of electromagnetic radiation (E)

= {{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

Q12

From the following pairs of ions which one is not an iso-electronic pair?

A Fe 2+ , Mn 2+

B O 2

-

, F

-

C Na + , Mg 2+

D Mn 2+ , Fe 3+

Correct Answer

Option A

Solution

$\bullet$ Isoelectronic species have some number of electrons.

Q13

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

Correct Answer

Option D

Solution

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.

Q14

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

Correct Answer

Option C

Solution

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.

Q15

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 dz 2 is zero.

Correct Answer

Option C

Solution

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

Q16

Which one is the wrong statement ?

A The uncertainty principle is

\Delta E \times \Delta t \ge {h \over {4\pi }}

B Half filled and fully filled orbitals have greater stability due to greater exchange energy, greater symmetry and more balanced arrangement.

C The energy of 2s-orbital is less than the energy of 2p-orbital in case of hydrogen like atoms.

D de-Broglie's wavelength is given by

\lambda = {h \over {mv}}

, where m = mass of the particle, v

=

group velocity of the particle.

Correct Answer

Option C

Solution

In the case of hydrogen type atoms, energy depends on the principal quantum number only.

Therefore 2-s orbital will have energy equal to 2-p orbital.

Q17

Which of the following pairs of d-orbitals will have electron density along the axes ?

A

{d_{{z^2}}},\,\,{d_{xz}}

B d xz ,

{d_{yz}}

C

{d_{{z^2}}},\,\,{d_{{x^2} - {y^2}}}

D

{d_{xy}},\,{d_{{x^2} - {y^2}}}

Correct Answer

Option C

Solution

d x 2 - y 2 and d z 2 orbitals have electron density along the axes.

Q18

How many electrons can fit in the orbital for which n = 3 and

l

= 1?

A 2

B 6

C 10

D 14

Correct Answer

Option B

Solution

For $n = 3$ and $l = 1$ : $n = 3$ means the electron is in the third shell $l = 1$ means it is a $p$ -subshell Now, for a $p$ -subshell: the possible values of $m_l$ are $-1, 0, +1$ so, number of orbitals $= 3$ Each orbital can hold a maximum of $2$ electrons.

So total electrons in the $3p$ subshell:

3 \times 2 = 6

Therefore, the correct answer is Option B: 6 .

Q19

Two electrons occupying the same orbital are distinguished by

A azimuthal quantum number

B spin quantum number

C principal quantum number

D magnetic quantum number

Correct Answer

Option B

Solution

For any two electrons occupying the same orbital values of n, l and m l are same but m s is different [ +

1 \over 2

and -

1 \over 2

]

Q20

Which is the correct order of increasing energy of the listed orbitals in the atom of titanium ? (At. no. Z = 22)

A 4s 3s 3p 3d

B 3s 3p 3d 4s

C 3s 3p 4s 3d

D 3s 4s 3p 3d

Correct Answer

Option C

Solution

Ti (22) $\Rightarrow$ 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 $\therefore$ Order of increasing energy is 3s, 3p, 4s, 3d