₉₀Th²²⁸ emits four alpha and one beta particles. Number of neutrons in daughter element is

• 129

• 190

• 232

• 138

Which of the ions is colourless inspite of the presence of unpaired electrons ?

• La³⁺

• Eu³⁺

• Gd³⁺

• Lu³⁺

Uncertainty in the position of an electron (mass= 9.1 x 10^-31 kg) moving with a velocity 300 ms^-1 accurate upon 0.001 % will be (h = 6.63 x 10^-34 J-s)

• 19.2 x 10^-2 m

• 5.76 x 10^-2 m

• 1.92 x 10^-2 m

• 3.84 x 10^-2 m

Uncertainty principle is valid for

• Proton

• Methane

• Both (a) and (b)

• 1 µm sized platinum particles

The energy of an electron is the 3S orbital ( excited state) of H- atom is

• -1.5 eV

• -13.6 eV

• -3.4 eV

• -4.53 eV

76.

In the hydrogen atom spectrum, the emission of the least energetic photon takes place during the transition from n = 6 energy level to n = .......... energy level.

• 1

• 3

• 5

• 4

The threshold frequency of a metal corresponds to the wavelength of x nm. In two separate experiments A and B, incident radiations of wavelengths 1/2x nm and 1/4x nm respectively are used. The ratio of kinetic energy of the released electrons in experiment 'B' to that in experiment 'A' is

• 1/3

• 2

• 4

• 3

The minimum values of uncertainties involved in the determination of both the position and velocity of a particle respectively are 1 × 10^-10 m and 1 × 10^-10 ms^-1.Then, the mass (in kg) of the particle is

• 5.270 × 10^-15

• 5.270 × 10^-20

• 5.270 × 10^-16

• 5.270 × 10^-10

The number of electrons with azimuthal quantum number l = 1 and l = 2 for Cr in ground state respectively are

• 12, 5

• 12, 4

• 16, 5

• 16, 4

In which one of the following, d-d transition involves absorption in the ultraviolet region?

• [Cu(H₂O)₄]²⁺

• [Ti(H₂O)₆]³⁺

• [Co(NH₃)₆]³⁺

• [Co(CN)₆]^3-