In nuclear explosion, the energy is released in the form of :

• kinetic energy

• electrical energy

• potential energy

• None of these

612.

The number of atoms in 52 g of He is

• 78.299 x 10²⁴atoms

• 7.820 x 10^-24atoms

• 7.829 x 10²⁴ atoms

• 78.234 x 10²⁵ atoms

Threshold frequency of a metal is 5 $\text{×}$ 10¹³ s^-1 upon which 1 x 10¹⁴s^-1 frequency light is focused. Then the maximum kinetic energy of emitted electron is

• 3.3 $\text{×}$ 10^-21

• 3.3 $\text{×}$ 10^-20

• 6.6 $\text{×}$ 10-²³

• 6.6 $\text{×}$ 10^-20

From elementary molecular orbital theory we can deduce the electronic configuration of the singly positive nitrogen molecular ion as :

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\pi }$2p⁴ , $\mathrm{\sigma }$2p¹

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p² , $\mathrm{\pi }$2p³

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p³ , $\mathrm{\pi }$2p²

• $\mathrm{\sigma }$1s² , $\stackrel{*}{\mathrm{\sigma }}$1s² , $\mathrm{\sigma }$2s² , $\stackrel{*}{\mathrm{\sigma }}$2s² , $\mathrm{\sigma }$2p² , $\mathrm{\pi }$2p⁴

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

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.