The time taken for an electron to complete one revolution in Bohr orbit of hydrogen atom is

• $\frac{4{\mathrm{m}}^2{\mathrm{\pi r}}^2}{{\mathrm{n}}^2{\mathrm{h}}^2}$

• $\frac{{\mathrm{n}}^2{\mathrm{h}}^2}{4{\mathrm{mr}}^2}$

• $\frac{4{\mathrm{\pi }}^2{\mathrm{mr}}^2}{\mathrm{nh}}$

• $\frac{\mathrm{nh}}{4{\mathrm{\pi }}^2{\mathrm{mr}}^2}$

Amongst the following, which should have the highest rms speed at the same temperature?

• SO₂

• CO₂

• O₂

• H₂

The emission spectrum of hydrogen discovered first and the region of the electromagnetic spectrum in which it belongs, respectively are

• Lyman, ultraviolet

• Lyman, visible

• Balmer, ultraviolet

• Balmer, visible

The electronic configuration of Cu is

• [Ne] 3s²,3p⁶,3d⁹,4s²

• [Ne] 3s²,3p⁶, 3d¹⁰, 4s¹

• [Ne] 3s²,3p⁶, 3d³,4s², 4p⁶

• [Ne] 3s²,3p⁶,3d⁵,4s²,4p⁴

As per de-Broglie's formula a macroscopic particle of mass 100 g and moving at a velocity of 100 cm s^-1 will have a wavelength of

• 6.6 x 10^-29 cm

• 6.6 x 10^-30 cm

• 6.6 x 10^-31 cm

• 6.6 x 10^-32 cm

286.

During the emission of a positron from a nucleus, the mass number of the daughter element remains the same but the atomic numbe

• is decreased by 1 unit

• is decreased by 2 units

• is increased by 1 unit

• remains unchanged

$\mathrm{\beta }$-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