The valence shell electronic configuration of Cr²⁺ ion is :

• 4s⁰3d⁴

• 3p⁶4s²

• 4s³3d²

• 4s²3d⁰

In Bohr's Orbit, $\frac{\mathrm{nh}}{2\mathrm{\pi }}$ indicates

• Momentum

• Kinetic energy

• Potential energy

• Angular momentum

An element with atomic number 84 and mass number 218 loses one a-particle and two $\mathrm{\beta }$-particles in three successive stages .The resulting element will have :

• at. no. 84 and mass no. 214

• at no. 82 and mass no. 214

• at. no. 84 and mass no. 218

• at. no. 82 and mass no. 218

A particle is moving 3 times faster than the speed of electron. If the ratio of wavelength of particle and electron is 1.8 x 10^-4 then particle is

• neutron

• $\mathrm{\alpha }$- particle

• deuteron

• tritium

95.

Assertion : Number of radial and angular nodes for 3p-orbital are 1, 1 respectively.

Reason : Number of radial and angular nodes depends only on principal quantum number.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : Bohr model fails in case of multielectron pecies.

Reason : It does not mention electron-electron interactions.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

The product formed is an isobar , if there is :

• 1 $\mathrm{\alpha }$ emission

• 1 $\mathrm{\beta }$ emission

• 1 $\mathrm{\alpha }$ and 1 $\mathrm{\beta }$ emission

• 2 $\mathrm{\alpha }$ and 2 $\mathrm{\beta }$ emission

When ${}_{13}{}^{27}\mathrm{Al}$ is bombarded with $\mathrm{\alpha }$ - particle , a radioactive isotope of phosphorus ${}_{15}{}^{30}\mathrm{P}$ is formed .Which particle is emitted along with ${}_{15}{}^{30}\mathrm{P}$ ?

• Deuteron

• Proton

• Electron

• Neutron

Smallest wavelength occurs for

• Lyman series

• Balmer series

• Paschen series

• Brackett series

Which of the following is wrong for Bohr model?

• It establishes stability of atom

• It is inconsistent with Heisenberg uncertainty principle.

• It explains the concept of spectral lines for hydrogen like species.

• Electrons behave as particle and wave