Test: Structure of Atom - NEET MCQ

Atomic no 24 is of Cr. Due to half filled orbital stability it doesnot follow Afbau rule so its configuration is 

The element with atomic number(Z) 17 & mass number (A) 35 is chlorine = 

The mass number A is defined as the total number of nucleons in an atom's nucleus, which consists of the sum of protons and neutrons.

Therefore, the correct expression is:

A = Z + n

• A = mass number
• Z = number of protons
• n = number of neutrons

ψ has no physical significance while ψ2 represnts the probability density of finding an electron.

In anomalous Zeeman effect the splitting of spectral lines occurs due to interaction of the applied magnetic field with the magnetic moment generated by the orbital and 'spin' motions of the electron.

E/m values of particle (α), electron (e) and protons (p) increase in the order α< p < e

The electronic configuration 1s²2s²2p¹ corresponds to an atom with 5 electrons, which is boron (atomic number 5).

Breaking it down:

• 1s² contributes 2 electrons.
• 2s² adds another 2 electrons, totalling 4.
• 2p¹ adds the final electron, making it 5 in total.

This matches boron's atomic number of 5.

Energy for any n shell = -2.18 x 10⁻¹⁸ )/n^'2 (') stands for raise to the power of therefore, E associated with 5 orbit = -2.18 x 10⁻¹⁸/5² = -2.18 × 10^-18/25 = -218 × 10^-20/25 = -8.72 x 10^-20J/atom

Isobars are atoms that have the same mass number (total number of protons and neutrons) but different atomic numbers (number of protons). This means they belong to different elements but have the same total nuclear charge.

For example:

• Chlorine-37 has a mass number of 37 and an atomic number of 17.
• Argon-37 has a mass number of 37 and an atomic number of 18.

Thus, chlorine-37 and argon-37 are isobars because they both have a mass number of 37 but different atomic numbers.

This is known as shielding effect. Inner lying electrons shields the positive charge reaching the outer most electrons.

In this question l=3 means the sub shell is f & n=4 means it is present in 4^th orbit.
Finally it is a 4f sub shell.
The no of orbital in f sub shell =2l+1
                                                = 2*3+1
                                                =7
Each orbital can accommodate 2 electrons.
  7*2 = 14 electrons.

Maximum number of electrons in a sub shell with l=3& n=4 (4f) is 14electrons.

Energy of orbital is determined by n+l value. The orbital having higher n+l value will have higher energy. If n+l value is same then orbital having higher n value will have higher energy.

Isotopes are atoms that have the same atomic number (number of protons) but different mass numbers due to varying numbers of neutrons.

• The atomic number determines the element's identity.
• The mass number is the total number of protons and neutrons in the nucleus.
• Isotopes can be stable or unstable (radioactive).

For example:

• Carbon-12 has 6 protons and 6 neutrons.
• Carbon-14 has 6 protons and 8 neutrons.

Both isotopes are forms of carbon, but their different numbers of neutrons affect their mass numbers and stability.

The Aufbau principle explains that electrons fill orbitals starting from the lowest energy level and moving upwards in order of increasing energy. This ensures stability in the atom's ground state, as lower energy levels are filled first before higher ones.

The radio frequency region used for broadcasting is typically around 10⁶ Hz (1 MHz). This includes:

• Common frequencies for AM radio
• Common frequencies for FM radio
• TV signals

This range falls within the broader radio wave spectrum, making option A correct.

It is Krypton .
Electronic configuration:  1s²2s²2p63s²3p64s²3d104p6
​Number of electrons in s orbital are 8
Number of electrons in p orbital are 18
Number of electrons in d orbitals are 10 (18-8=10)

The photoelectric effect demonstrated that light consists of photons, which are particles that carry quantized energy.

The energy of a photon is given by the equation:

E = hf

This was a fundamental discovery by Albert Einstein, showing that light exhibits particle-like properties under certain conditions.

Paulis exclusion principle stated that no two electron can have same set of all the four quantum nos.

The s-orbital is spherically symmetrical, meaning it has no specific direction and is non-directional.

For hydrogen atom =  2.18 x 10⁻¹⁸J atom⁻¹ =−E_1(H)

+3 charge means no of electrons will be 3 less than no. of protons. So no. of protons will be 21. So atomic no. is 21.

Emission spectrum is recorded when a electron de excites from higher energy level to ground state.

Dalton’s atomic theory stated that atoms were indivisible. However, the discovery of subatomic particles (such as protons, electrons, and neutrons) disproved this postulate.