31 Year NEET Previous Questions: Structure of Atom - 2 Free MCQ Practice

Both He and Li⁺ contain 2 electrons each therefore their spectrum will be similar.

No. of radial nodes in 3p-orbital = (n – ℓ – 1) [for p ortbital ℓ = 1] = 3 – 1 – 1 = 1

According to Bohr's Model:
r ∝n²/Z
So, radius of nth orbit is r_n=rn², as Z=1 for H atom.

is uncertainty principle which was given by Hiesenberg and not Bohr’s postulate

No. of orbitals in a sub-shell = 2 ℓ + 1

⇒ No. of electrons = 2(2ℓ + 1) = 4ℓ + 2

n = 2, l = 1 means 2 p – orbital. Electrons that can be accommodated = 6 as p sub-shell has 3 orbital and each orbital contains 2 electrons.

Cu⁺ = 29 – 1 = 28 e^– thus the electronic confingration of Cu⁺ is

This is as per the definiti on of Paul i’s Exclusion princieple.

ℓ = 3 means f-subshell. Maximum no. of electrons = 4ℓ + 2 = 4 × 3 + 2 = 14

The sub-shell with lowest value of (n + ℓ) is filled up first. When two or more sub-shells have same (n + ℓ) value the subshell with lowest value of 'n' is filled up first therefore the correct order is

Energy of an electron in Bohr's orbit is given by the relationship. 

Lone pair of electron means 2 electron(since it is pair)
For 4 lone pair electrons, we need 8 electrons in the outer shell. This is possible only with Cl- as it neutral Cl has 7 electrons and with addition of an electron they are 8 in number or 4 lone pairs of electrons.

The ionization energy of any hydrogen like species (having one electron only) is given by the equation

Since the atomic number of H is 1 and that of He is 2, therefore, the I.E. of He⁺ is four times (22) the I.E. of H i.e., 13.6 × 4 = 54.4 eV

The sub-shell are 3d, 4d, 4p and 4s, 4d has highest energy as n + ℓ value is maximum for this.

Cathode r ays are never electromagnetic waves.

Wave nature of electr on was shown by Davisson and Germer. Davission and germer demonstrated the physical reality of the wave nature of electrons by showing that a beam of electrons could also diffracted by crystals just like light of x-rays.

P.E. = work done  

K.E. of emitted electron = hν - hν₀ (i.e. smaller than hν ).

It cannot be present in s-orbital.

State of hydrogen atom (n) = 1 (due to ground state) Radius of hydrogen atom (r) = 0.53 Å.
Atomic number of Li (Z) = 3.
Radius of Li²⁺ ion

Given mass of an electron(m) = 9.1x10 ^-28g; Velocity of electron (v) = 3 x10⁴cm/s;

Accuracy in velocity  = 0.001%

Actual velocity of the electron

.Planck’s constant (h) = 6.626×10^–27erg-sec.

∴  Uncertainty in the position of the electron

=1.93cm

The orbitals which have same energy are called degenerate orbitals eg. px , py , pz .

Acc. to deBroglie

.

⇒   p = 6.626 × 10^–17 kg m/s

We know that ions which have th e same number of electrons are called isoelectronic.
We also know that both CO and CN^– have 14 electrons, therefore these are isoelectronic.

Given : Radius of hydrogen atom = 0.530 Å,
Number of excited state (n) = 2 and atomic number of hydrogen atom (Z) = 1. We know that the Bohr radius.

= 4 x 0.530 = 2.12 Å

By Heisenberg uncertainty Principle

(which is constant)

As Δx for electron and helium atom is same thus momentum of electron and helium will also be same therefore the momentum of helium atom is equal to 5 × 10^–26 kg. m.s^–1.

Energy of electron in 2nd or bit of Li⁺²

Energy required = 0 – (–30.6) = 30.6 eV

The energy of photon,

The molecule which contains same number of electrons are called isoelectronic. eg.