The energy of an electron in n^th orbit of hydrogen atom is

• $\frac{13.6}{{\mathrm{n}}^4}\mathrm{eV}$

• $\frac{13.6}{{\mathrm{n}}^3}\mathrm{eV}$

• $-\frac{13.6}{{\mathrm{n}}^2}\mathrm{eV}$

• $\frac{13.6}{\mathrm{n}}\mathrm{eV}$

Which of the following is not iso-electronic?

• Na⁺

• Mg²⁺

• O^2-

• Cl^-

Which of the following equations represent de-Broglie relation?

• $\frac{\mathrm{h}}{\mathrm{mv}}=\mathrm{p}$

• $\mathrm{\lambda m} =\frac{\mathrm{v}}{\mathrm{p}}$

• $\mathrm{\lambda }=\frac{\mathrm{h}}{\mathrm{mp}}$

• $\mathrm{\lambda }=\frac{\mathrm{h}}{\mathrm{mv}}$

Which of the following sequences of the energy levels of the subshells related to principal quantum number four (n = 4)?

• s< p< d< f

• s< d< p< f

• s< f< p< d

• p< s< d< f

The correct electronic configuration of iron is

• 1s², 2s² 2p⁶,3s² 3p⁶, 4s², 3d⁶

• 1s², 2s² 2p⁶,3s² 3p⁶, 4s², 3d⁵

• 1s², 2s² 2p⁶,3s² 3p⁶, 4s², 3d⁷

• 1s², 2s² 2p⁶,3s² 3p⁶, 4s², 3d⁵

Which of the electronic shell of the following elements is not rounded?

• He

• Be

• B

• Li

In a radioactive change $\mathrm{R} \stackrel{-\mathrm{\alpha }}{\to } \mathrm{X} \stackrel{-\mathrm{\beta }}{\to } \mathrm{Y} \stackrel{-\mathrm{\beta }}{\to } \mathrm{Z}$. R and Z.

• isotopes

• isobars

• isomers

• isotones

_nX^m emit one α and two β- particles. It is converted into

• _nX^{m - 4}

• _{n - 1}X^{m - 1}

• _nZ^{m - 4}

• None of these

149.

Increasing order (lowest first) for the values of e/m for electron (e), proton (p), neutron (n) and α-particles is

• e, p, n, α

• n, α, p, e

• n, p, e, α

• n, p, α, e

A particle moving with a velocity 10⁶ m/s will have de-Broglie wavelength nearly [Given, m= 6.62 × 10^-27 kg, h =  6.62 × 10^-34 J-s]

• 10^-9m

• 10^-13 m

• 10^-19 m

• 1 Å