381.

₇₂X¹⁸⁰ $\stackrel{2\mathrm{\alpha }}{\to }$ $\stackrel{\mathrm{\beta }}{\to }$ $\stackrel{\mathrm{\gamma }}{\to }$ _zX^A , Z and A are :

• 69 , 172

• 172 , 69

• 180 , 70

• 182 , 68

Assertion : The quantized energy of an electron is largely determined by its principal quantum number.

Reason : The principal quantum number n is a measure of the most probable distance of finding the electron around the nucleus.

• 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 : C- O bond in metal carbonyl is long.

Reason : There is delocalisation of electrons from filled d orbitals into the empty orbitals on the CO ligands.

• 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.

Isotopic pair is :

• ₂₀X⁴⁰ , ₂₁X⁴⁰

• ₂₀X⁴⁰ _{, 20}X⁴¹

• ₄₀X²⁰ , ₄₁X²⁰

• None

Atomic number of an element is equal to the number of :

• protons

• neutrons

• electrons

• protons + neutrons

Radioactive isotope of hydrogen is :

• Uranium

• Deuterium

• Tritium

• None

Electronk configuration of hydride ion is :

• 1s^o

• 1s¹

• 1s²

• 1s¹2s¹

The de Broglie wavelength associated with a ball of mass 1kg having kinetic energy 0.5 J is

• 6.626 $\times$ 10^-34 m.

• 13.20 $\times$ 10^-34 m.

• 10.38 $\times$ 10^-21m.

• 6.626 $\times$10^-34$\stackrel{°}{\mathrm{A}}$.

Wave nature of electrons was demonstrated by :

• Schrodinger

• De-Broglie

• Davisson and Garmer

• Heisenberg

${}_{92}{}^{238}\mathrm{U}$ emits 8 α-particles and 6 β-particles. The neutron/proton ratio in the product nucleus is

• 60/41

• 61/40

• 62/41

• 61/42