$\mathrm{\beta }$-emission is always accompanied by

• formation of antineutrino and $\mathrm{\alpha }$-particle

• emission of $\mathrm{\alpha }$-particle and $\mathrm{\gamma }$-ray

• formation of antineutrino and $\mathrm{\gamma }$-ray

• formation of antineutrino and positron

An atomic nucleus having low n/p ratio tries to find stability by

• the emission of an $\mathrm{\alpha }$-particle

• the emission of a positron

• capturing an orbital electron (K-electron capture)

• emission of a $\mathrm{\beta }$-particle

$( {}_{32}\mathrm{G}^{76}, {}_{34}\mathrm{Se}^{76}) \mathrm{and} ( {}_{14}\mathrm{Si}^{30}, {}_{16}\mathrm{S}^{32})$are example of 

• isotopes and isobars

• isobars and isotones

• isotones and isotopes

• isobars and isotopes

₉₈Cf²⁴⁶  was formed along with a neutron when an unknown radioactive substance was bombarded with ₆C¹². The unknown substance was 

• ₉₁Pa²³⁴

• ₉₀Th²³⁴

• ₉₂U²³⁵

• ₉₂U²³⁸

Identify the correct statement.

• Quantum numbers (n, l, m, s) are arbitrarily

• All the quantum numbers (n, l, m, s) for any pair of electron in an atom can be identical under special circumstance

• All the quantum numbers (n, l, m, s) may not be required to describe an electron of an atom completely

• All the quantum numbers (n, l, m, s) are required to describe an electron of an atom completely

${}_{11}\mathrm{Na}^{24}$ is radioactive and it decays to 

• ${}_9\mathrm{F}^{20} \mathrm{and} \mathrm{\alpha }- \mathrm{practicle}$

• ${}_{13}\mathrm{Al}^{24} \mathrm{and} \mathrm{positron}$

• ${}_{11}\mathrm{Na}^{23} \mathrm{and} \mathrm{neutron}$

• ${}_{12}\mathrm{Mg}^{24} \mathrm{and} \mathrm{\beta }- \mathrm{parcticles}$

Which one of the following characteristics belongs to an electrophile?

• It is any species having electron deficiency which reacts at an electron rich C-centre

• It is any species having electron enrichment, that reacts at an electron deficient C-centre

• It is cationic in nature

• It is anionic in nature

Which of the following does not represent the mathematical expression for the Heisenberg uncertainty principle?

• $∆\mathrm{x}·∆\mathrm{P}\ge \mathrm{h}/ \left(4\mathrm{\pi }\right)$

• $∆\mathrm{x}·∆\mathrm{\nu }\ge \mathrm{h}/\left(4\mathrm{\pi m}\right)$

• $∆\mathrm{E}·∆\mathrm{t}\ge \mathrm{h}/\left(4\mathrm{\pi }\right)$

• $∆\mathrm{E}·∆\mathrm{x}\ge \mathrm{h}\left(4\mathrm{\pi }\right)$

39.

The energy of an electron in first Bohr orbit of H-atom is -13.6 eV. The possible energy value of electron in the excited state of Li²⁺ is

• -122.4 eV

• 30.6 eV

• -30.6 eV

• 13.6 eV

The representation of the ground state electronic configuration of He by box-diagram as  is wrong because it violates

• Heisenberg's uncertainty principle

• Bohr's quantization theory of angular momenta

• Pauli exclusion principle

• Hund's rule