NEET Chemistry Questions: Structure of Atom

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The maximum number of electrons in a subshell is given by the expression





The maximum number of electrons in a subshell is given by the expression 4l + 2, where l is the azimuthal quantum number. This is known as the 'Pauli Exclusion Principle', which states that no two electrons in an atom can have the same set of four quantum numbers.
If r is the radius of first orbit, the radius of nth orbit of the H atom will be (C.B.S.E. 1989)




No explanation available.
The energy of hydrogen atom in its ground state is -13·6 eV. The energy of the level corresponding to the quantum number n= 5 is




The energy of the hydrogen atom in its ground state (n=1) is -13.6 eV. The energy of the level corresponding to the quantum number n is given by E = (-13.6 eV)/n^2. For n=5, the energy will be (-13.6 eV)/5^2 = 0.54 eV.
At $200 ^\circ C hydrogen molecules have velocity 105 cm sec^{-1} $ . The de-Broglie wavelength in this case is approximately




No explanation available.
In a set of degenerate orbitals the electrons distribute themselves to retain similar spins as far as possible. This statement is attributed to




Hund's rule states that for degenerate orbitals (orbitals with the same energy), the electrons occupy the orbitals in such a way that their spins are parallel, maximizing the total spin multiplicity. This rule is based on the principle of maximum multiplicity, which leads to greater stability.
If uncertainty in the position of electron is zero, the uncertainty in its momentum would be




According to the Heisenberg Uncertainty Principle, the position and momentum of a particle cannot be measured with absolute precision simultaneously. If the uncertainty in the position of an electron is zero, it implies that its position is known exactly, leading to an infinite uncertainty in its momentum.
The radius of second Bohr’s orbit is




No explanation available.
For which of the following sets of quantum -numbers an electron will have the highest energy ?




No explanation available.
The uncertainty in the position of an electron $ (mass 9.1 \times 10^{–28} g) $ moving with a velocity of $ 3.0 \times10^4 cms^{–1} $ accurate up to 0.011% will be




The uncertainty in the position of a particle is given by the Heisenberg Uncertainty Principle: Δx * Δp ≥ h/4π, where Δx is the uncertainty in position, Δp is the uncertainty in momentum, and h is Planck's constant. Using the given values and the relation p = mv, the uncertainty in position is calculated to be 0.175 cm.
The radius of hydrogen atom in the ground state is $ 0·53 A ^ \circ , the radius of 3_Li ^{2+} $ in the similar state is




The radius of a hydrogen-like atom is inversely proportional to the nuclear charge (Z). For the Li2+ ion, Z = 3. Since the radius of the hydrogen atom is given as 0.53 Å, the radius of Li2+ in the ground state will be 0.53/3 = 0.17 Å.
Splitting of spectral lines under the influence of magnetic field is called




The splitting of spectral lines due to the influence of a magnetic field is known as the Zeeman effect. It is caused by the interaction between the magnetic dipole moment of the electron and the applied magnetic field.
The total number of orbitals in a shell with principal quantum number ‘n’ is




No explanation available.
Which of the following expressions gives the de-Brogiie relationship ?




The de-Broglie relationship relates the wavelength (λ) of a particle with its momentum (p) as λ = h/p, where h is the Planck's constant. By substituting p = mv, we get λ = h/mv, which is the correct expression relating wavelength, mass, and velocity of a particle.
The uncertainty in the momentum of an electron is $ 1·0 \times 10^{–5} kg ms^{–1}. The uncertainty in its position will be (h = 6·62 \times 10^{–34} kg m^2s^{–1} )$




No explanation available.
If the radius of first Bohr orbit be $a_0$ , then the radius of third Bohr orbit would be




Radius of Bohr orbit $ = { n ^ 2 \over Z } \times a_0 $