Structure Of Atom JEE Main Chemistry: Authentic Shift PYQs (2021-2026) with 2.5-Min Shortcut Tricks & Trap Defense

Correct Answer: d

Explanation: an electron The Heisenberg uncertainty principle is commonly applied to position and momentum of a particle .

Correct Answer: 2

Explanation: Concept: The de Broglie wavelength of a charged particle depends inversely on the square root of its mass when the accelerating potential is the same. Explanation: The de Broglie wavelength formula is $\lambda = \frac{h}{\sqrt{2mK}}$ . Here, $h$ is Planck's constant and $K$ is the kinetic energy. Both particles $m_1$ and $m_2$ are accelerated through the same potential difference of 200 keV. Therefore, they acquire the same kinetic energy $K$ . Since $h$ and $K$ are identical for both particles, $\lambda \propto \frac{1}{\sqrt{m}}$ . Mass of $m_1$ is 1 amu and mass of $m_2$ is 4 amu. The ratio of their wavelengths is: $\frac{\lambda_{m_1}}{\lambda_{m_2}} = \sqrt{\frac{m_2}{m_1}} = \sqrt{\frac{4}{1}} = 2$ . Thus, $\lambda_{m_1} = 2 \times \lambda_{m_2}$ . This means the de Broglie wavelength of $m_1$ is 2 times that of $m_2$ . Shortcut: For constant kinetic energy, $\lambda \propto \frac{1}{\sqrt{m}}$ . Given the mass ratio $m_2 : m_1 = 4 : 1$ . The wavelength ratio is $\lambda_{m_1} : \lambda_{m_2} = \sqrt{m_2} : \sqrt{m_1} = 2 : 1$ . Therefore, $\lambda_{m_1} = 2 \cdot \lambda_{m_2}$ . Answer: $x = 2$ (Option A)

Correct Answer: b

Explanation: $\psi_{2 s}^{2} =$ Probability of finding an electron within 2s sphere   $\psi_{2 s}^{2} =$ 0 (at node) As probability of finding an electron is zero at node $0 = \frac{1}{4 \sqrt{2 \pi}} \left(\frac{1}{a_{0}}\right)^{\frac{3}{2}} \left(2 - \frac{r_{0}}{a_{0}}\right) e^{- \frac{r_{0}}{a_{0}}}$ On solving, $\left(2 - \frac{r_{0}}{a_{0}}\right) = 0$ $\therefore 2 = \frac{r_{0}}{a_{0}}$ ​​​2a<$_{0}$ = r<$_{0}$ Hence, x = 2

Correct Answer: c

Explanation: nucleus Rutherford's experiment on scattering of α-particles showed for the first time that the atom has  positively charged nucleus . He observed that the positively charged α-particles were repelled and deflected by the positive charges in the atom which he  named this  as nucleus.

Correct Answer: b

Explanation: Solution of Schrödinger principle ​Solution of Schrodinger equation gives us three quantum numbers n, l and m$_{l}$.​