51.

When an electron jumps from the orbit n = 2 to n = 4, then wavelength of the radiations absorbed will be (R is Rydberg's constant)

• $\frac{16}{3\mathrm{R}}$

• $\frac{16}{5\mathrm{R}}$

• $\frac{5\mathrm{R}}{16}$

• $\frac{3\mathrm{R}}{16}$

The thermonuclear reaction of hydrogen inside the stars is taking place by a cycle of operations. The particular element which acts as a catalyst is

• Nitrogen

• Oxygen

• Helium

• Carbon

The ratio of minimum wavelengths of Lyman and Balmer series will be

• 1.25

• 0.25

• 5

• 10

The fraction of the initial number of radioactive nuclei which remain undecayed after half of a half-life of the radioactive sample is

• $\frac{1}{4}$

• $\frac{1}{2\sqrt{2}}$

• $\frac{1}{2}$

• $\frac{1}{\sqrt{2}}$

1 curie represents

• 3.7 × 10⁷ disintegrations per second

• 3.7 × 10¹⁰ disintegrations per second

• 10⁶ disintegrations per second

• 1 disintegrations per second

An n-p-n transistor can be considered to be equivalent to two diodes, connected. Which of the following figure is the correct one ?

In the case of forward biasing of a p-n junction diode, which one of the following figures correctly depicts the direction of conventional current (indicated by an arrow mark) ?

An electron of mass m_e and a proton of mass m_p are moving with the same speed. The ratio of their de-Broglie's wavelengths λ_e/ λ_p is

• 1

• 1836

• $\frac{1}{1836}$

• 918

The output of given logic circuit is

• A . (B + C)

• A . (B . C)

• (A + B) . (A + C)

• A + B + C

If the scattering intensity of a liquid is 8 units at a wavelength of 500 nm, then the scattering intensity at a wavelength of 400 nm will be approximately

• 13 units

• 16 units

• 20 units

• 24 units